I have recently been playing (!) with a BSA Scorpion pistol that was in a very sorry state: the piston had seized in the cylinder, the buffer washer on the piston had disintegrated, there was no safety spring and the trigger assembly was clearly wrong.
Stripping the Scorpion has been covered by Guy (ggggr) in the excellent 'Idiot's Guide' sticky on this forum so I will not go into that part, but I failed to find instructions on how the trigger goes together .. and thanks are due here to Troubledshooter for his help with pictures showing how the safety spring fits and to Guy for his helpful comments as I battled with my pistol.
So ... lets assume you have stripped the pistol, the safety catch lever is removed (it has to come off to strip the pistol), you have split the trigger housing from the cylinder and for whatever reason want to remove the trigger/sear parts. First thing: think about it! Do you really need to do this? It is not easy ... you may get it done in a few minutes, you may sweat away for hours to get the bits back correctly. Assuming you want to do it: With a small punch or screwdriver push out the pin that holds the sears inside the housing. There is no need to remove the trigger itself unless you want to and if you do, just push out the trigger pivot pin and it comes away quite easily ... take care not to lose the spring in the trigger blade. The trigger bar will separate from the trigger ... it goes back 'straight side' up towards the cylinder.
With the sears pin out and your prod removed, the bits will fall apart .. you will have the pivot pin, a spacing washer, a spring, a small sear and the hammer (bigger bit). Once removed, the safety can be removed.Chambers show an exploded diagram.
Now, before trying to assemble the bits, make a 'slave pin' the same diameter as the pivot pin and just long enough to fit snuggly between the sides of the trigger housing. Without this you may as well give up. I made mine from a nail.
Step 1: fit trigger, if you removed it, and insert the safety bar and fit the catch lever. Get some fine wire and put it through the hole that the safety spring locates in. This is all to stop the catch falling out as you fiddle with the other bits.
Step 2: Hold your slave pin and add the hammer with the long prong pointing away from you and the small peg on the hammer on the underside, the hammer notches will be to the left. Add the small sear from underneath with its longer end away from you and bending towards the right... arrange it so that the right hand edge of the sear fits against the lhs of the peg on the hammer. Add the washer on top of the hammer. Fit the spring: the hooked end goes around the base of the hammer and the simple bent end needs to be fitted so that it rests on the left hand edge of the small sear. This is fiddly as it has a tendency to slip off. Now, holding all this together between finger and thumb, insert it into the trigger housing from the top and to the right of the trigger bar. The hammer long prong will be upwards and will be close to you. Carefully slide it down ... the long tang on the hammer is good for this. Take care that the spring end does not ping off the edge of the small sear. If it does, start again. Keep wiggling the assembly down and towards the trigger bar. You will reach a point when you must take care that the sears are going to fit inside the cut out on the safety bar. Keep wiggling, with help from a small screwdriver, until you can see your slave pin next to the holes in the housing that the sear pivot pin goes it. This can be fun. Take the pivot pin and hold it in the housing hole next to the washer. Keep fiddling with the position of your slave pin until the true pin can be pushed in. It helps to keep the hammer at its 'at rest position' with regard to the trigger bar i.e. trigger bar on top of the first notch of the hammer. You may achieve a perfect push first time ... more likely you will get your pin through the washer but then have to continue jiggling until it pushes the slave pin all the way out. Job done. Sounds easy! Check for working ... you can cock the trigger by pushing the long arm of the hammer down to the right. It cocks onto the second notch. Check action with safety spring fitted. I found it easier to remove the long sear from the trigger housing to do the sear assembly, it can flap around otherwise or may even fall off if the pin comes out. If you removed it, refit it now and if all is well, refit housing to the action.
Hopefully all will be well but I know from experience that the safety catch can be temperamental .....
Cheers, Phil