I am adding this due to an interest in Collectables.

Warning: taking this rifle apart is not difficult but putting the receiver components back together can be very fiddly, so if you are prepared to take the task on, give yourself plenty of time. Renewing the pump head seal is easy with no pitfalls.

Pump head seal: You need to remove the complete pump assembly, but there is no need to strip the receiver components. Remove the band that holds the barrel to the pump tube, one screw secures the two halves. Pull off the black cap underneath the band halves. There is a roll pin holding the pump rod link to the pump cylinder. Remove the pin. Remove a black plastic end cap from the pump cylinder tube and pull the pump assembly out of the cylinder. The pump head seal is a push fit on the end of the assembly ... part 760-140 (same part for the Crosman 2100, 760 and 766 and most likely other Crosman rifles). Reassembly is simply a reversal of these steps.

Parts inside receiver: To replace most receiver parts there is no need to remove the pump assembly. However, if you wish to service or replace the valve assembly or transfer port then you should remove the pump assembly as it makes handling so much easier.

To split the receiver halves, remove the three screws from the lh receiver side but keep the halves together. Place the rifle lh side down on a table and slowly begin to lift the rh receiver side up from the lh side. As you do this, watch out for the sear spring which will appear in the gap between the two halves just in front of the trigger housing. It is unlikely to ping away, but be prepared as it will almost certainly emerge through the gap as you separate the receiver halves. Continue lifting the rh receiver until it comes away over the cocking lever. You will be left with the trigger, sears, valve and hammer mechanisms in place on the lh receiver. All reassembly operations must be done with the lh receiver flat on the table, assembling the parts on this part before adding the rh receiver.

Lift away the little black plastic ring that holds the pump arm firm on the right side of the receiver. Do not forget it.

Lift away the sear spring mentioned earlier, noting that it locates on a peg on the underside of the sear bar. Lift away the steel right angled black part (trigger bar) sitting on top of the sear bar, then a washer, then the sear bar. There is no need to remove the trigger blade and the safety catch and catch spring. They will sit where they are quite happily.

Before continuing, look at how the pump tube and barrel assembly lies in the receiver; hopefully it will not have jolted free when you split the halves. Note the lh end hole in the pump tube and the black plastic part visible through the hole and the end of the tube. This is a spring guide for the hammer spring. The sides of this guide are flat and have a hole passing through them. One of the receiver securing screws passes through this hole. To access the valve mechanism, lift the barrel and pump tube away from the receiver. As you do this, the hammer and its spring will push the black plastic guide out of the tube, but they should not ‘ping away’. The hammer cocking lever and pellet probe assembly ... the black plastic bits that sit on top and rear of the barrel will lift away at the same time. The barrel and pump tube are not secured together and can be simply separated. No doubt the cocking lever parts will fall away as well but do not panic. Lift barrel off the pump tube. The transfer port should remain secure inside the valve housing that is in the pump tube. Remove the hammer, hammer spring and spring guide.

My valve housing, situated in the lh end of the pump tube, had a blow off valve fitted to the underside of the main valve housing; a brass cylinder about 12mm long x 8mm diameter dangling from the underside of the pump tube. It is a push fit in the valve housing so just pull it free. To access and service the valve mechanism you must push the valve (dowel will do it), towards the rh end of the pump tube; it simply pops out. Note the hammer pin at the lh end and a domed rh end with O ring seal. To access the inside of the valve, the rh end (domed) part unscrews but it may be tight. There is another O ring to seal this end part into the valve cylinder. Kits are available containing all the parts needed to service the valve, although if you suspect the valve itself is OK it may be worth trying just a new O ring on the valve body to give a better seal against the pump tube.
Look at the transfer port on the valve body; there should be a seal inside. Renew it if it looks worn.

Reassembly: When you are satisfied with the valve mechanism, replace it in the pump tube, apply a little Pelgun oil to the sealing O ring and push the valve back down the tube ... hammer pin to the left. Take care not to nick the O ring on the pump slot as you do so. Make sure the transfer port lines up with its hole in the tube. Now is a good time to replace the blow off valve, if fitted. Simply push it back into place under the valve assembly.

Place the hammer, spring and spring guide into the pump tube. Add the cocking lever components onto the top of the barrel assembly. Reassemble the barrel to the pump tube, making sure transfer tube on the barrel sits inside the port on the tube and that the peg on the hammer locates in the slot in the cocking lever assembly and that when you move the cocking lever to the left it takes the hammer with it. Get the lh receiver part, complete with stock attached, ready in front of you on the table. Now, hold the tube and barrel assembly in your right hand and with your left hand push the spring guide into the tube, making sure the flat sides of the guide are facing up and down so that when you push the guide into the tube you can see the hole in the guide through the hole on top of the tube. While holding the barrel and tube in position with the spring guide, lower the assembly onto the lh receiver such that the hole in the underside of the lh end of the tube locates on the peg in the receiver. It should go neatly into place, retaining the spring guide as it does so. It will, hopefully, stay put while you continue:

Replace the pin for the trigger sear bar in its hole, followed by the sear bar, a washer, and the right angled black trigger bar on top. The rounded flat section points to the top of the action, the side with a bent end goes on bottom left. Locate the trigger sear bar ‘sears’ into the slot on the underside of the pump tube. Now ... before you forget, replace the pump lever holding bit on the right side of the receiver. So far, so good. Now for the fiddly bits.

Replace the sear spring... over the lower peg on the sear bar and tucked onto the underside (bottom edge) of the lh receiver. Now slowly add the rh receiver part, keeping it flat as you first pass it over the cocking arm and then locate the lh side where it goes into the stock. Lower it onto the lh receiver side. Keep pushing down until the bottom edge, closest to you is just touching the top of the sear spring. You now need to push this spring back into the receiver as you continue to lower the rh receiver onto the lh one. Push it correctly and the receiver will come down far enough to hold the spring in place. I can now guarantee that the left hand side has become stuck because the safety catch is not locating in its hole in the rh receiver part. You need to get a small screwdriver or needle and tease the safety catch into position to allow the rh receiver to fall/push onto the lh one. Hopefully, as the receiver halves come together, the sear spring will take up its correct position in the receiver. But be warned: it is very easy to trap a coil or part coil of this spring as you bring the receiver halves together. Attempts to correct this by holding the receivers apart while you try to fiddle the spring into position are doomed to failure; the spring may come adrift of the sear or flip over completely. Far better to admit defeat and start again.

But, hopefully, you have succeeded. Now, holding the receiver halves together, cock the trigger and check it works (Do not pump air in). Success? Now add the central screw that holds the stock halves together. Try cocking and firing again a few times. If this fails, it shows that the trigger bar and sear bar have not seated correctly. The only cure is to start again.

If you removed the pump assembly, replace it along with the end band.

Job done ...

Cheers, Phil