Not sure if this is a collectable yet, but here are some notes I made after a strip and clean of an auction find: Sorry, no pictures. It can help to look at the Chambers parts diagram.
NOTES ON DISMANTLING AND REBUILD OF ORIGINAL 45

STOCK REMOVAL
2 screws front. Rear pin goes though the trigger. On our model it looks like a bolt with allen heads as the bushes the pin goes into are a bit mangled. But it is a pin that is drifted out.

SPRING AND PISTON REMOVAL
To gain access to the spring and piston, the trigger must be removed. This is best done with rifle secured and trigger pointing up.
With the barrel to your left:
Remove circlip holding the trigger unit to the end block (2nd circlip from left ... quite clear)
Release and remove spring on extreme left... simple
Lift trigger unit away

The spring preload is not excessive but I found it easier to use a spring compressor.
Use compressor to hold end block in place ... in effect this means holding against the safety block. I used a piece of wood to get a good contact on the straight edge.
Push out the two pins holding the block in position. This releases the safety leaf spring, but do not worry, it will not ping away but remain in the safety slide.
Release spring tension.
The end block with safety slide comes out, with the spring guide and spring. Remove the parts, noting which way round the end block goes in relation to the spring guide. The safety slide comes away from the spring guide. Do not lose the leaf spring.

To remove the piston, the cocking arm must be released. I released it at the breech block end by pushing the pin out. The pin is held in place with a circlip but this was missing on our rifle. Remove cocking arm.
The piston can be slid out.
The piston has a sleeve. If you remove the sleeve, take care that you do not lose the cocking shoe (about 2cm long x 6mm wide) as it is held in place on the piston by the sleeve.

Service as you wish.

REASSEMBLY

This is basically a reverse of the above but these notes may help.

Refitting the cocking shoe: A bit fiddly. I found it best to insert the piston body into the cylinder (not fully!), hold rifle upside down above my head, then add the cocking shoe (right way round) and jiggle it so that it lay in position in the slot of the piston. Then, still with the rifle upside down, add the piston sleeve. With care it is possible to slide the sleeve into the piston so that it goes over the cocking shoe and hold it in place.

Refitting piston and end block: With piston shoe fixed, replace rifle in compressor, barrel to the left and trigger housing such that the trigger will point up, and add the spring. At this point I refitted the cocking arm. Add spring.
Add the spring guide, flat uppermost, and end block, making sure the end block is positioned correctly with the lugs over the flat of the guide. Add the safety slide, making sure the slide fits snugly in the guide and that the safety is the right way up (leaf spring slot pointing up) Compress spring to bring the two pin slots into alignment. Take care when doing this that the flat on the spring guide stays true to the end block. I used a punch to hold and align the left pin holes. Insert pin in the left hole.
Now you can add the leaf spring for the safety. I used a punch to hold the legs of the spring apart, then introduced the spring such that the legs went either side of the pin just fitted. The spring ‘crinkle’ should be pointing up. The spring is now held by just the ‘crinkle’ on its left.
Release the compressor tension. Carefully pull the safety slide out to allow the rest of the leaf spring to be pushed down into the safety slot. Push safety in. It is now possible to fit the second pin through the block, with the pin passing through the leaf spring. This can be a little fiddly. Do not hammer it through. I found it easier to use a torch to see how the pin was aligning with the holes and to use the spring compressor to just add or release a little tension such that the pin slides easily into place.
Release spring compressor and check that the safety slide moves easily in and out.

Refitting trigger: Not a problem but a bit fiddly to get the pin in place. Slide trigger unit into position in the end block and add the pin. I used a drift to first locate the pin holes then carefully pushed the pin into place. You may need to jiggle the position of the trigger unit to get the pin to locate.
Refit circlip. Refit the spring on the left of trigger unit.

Refit action to stock: Simple but take care that the pin through the trigger has a clear path. This can be achieved by slightly moving the trigger and using a drift to align everything. Refit the stock pin and screws.

Job done.
Cheers, Phil