MicrobeHunter.com Microscopy Forum

So the spring mechanism of retraction of the 40X Zeiss Neofluar starts to fail. The barrel retracts under pressure, but stays up and must be pulled to return to normal position.
In the Olympus SB objectives, the end cap serves as retainer for the spring. When the end cap is removed the spring pops out.
In the above mentioned Zeiss objective, the end cap is just a cap... below it, a more massive, metallic (I think) two-hole threaded ring forms the rear barrier to the spring.

That end cap is a thin fragile plastic thing, that sits flush with the rim of the objective thread, and difficult to remove with tools.

Forum member ImperatoRex has shown a very elegant trick to unscrew and remove the end cap, by pressing the objective against a triple layer of double sided adhesive tape and turning (CCW). I tried it - and it worked like a charm !!

Yet now I wonder how to continue. The shroud of the objective is very tight, so it would need rubber bands etc and some force to turn and remove and expose the front end of the spring, and take out the spring, without ruining the optics (like imperfect reassembly etc). I believe the spring should not be oiled. Perhaps just wipe it by insertion of a a Kimwipe piece round a Q-tip ?

P.S. it is a dry objective. The chance that it ever plunged into immersion oil is negligible.

So I followed the reasoning and advices posted by Apochronaut about a year ago,
and removed the shroud. I wrapped the barrel and shroud, each with a strip of 5mm thick leather (taken from an old belt), gripped each with a curved (or semi-curved) 10" vise-grip (one from Franklin, Japan, the other some unnamed replica). Gradually adjusted and tightened the vises to an extent that I thought might be exaggerated, but it proved to be correct; and forcibly rotated CCW. and, again like a charm, the elements were separated. 10" seems to be an appropriate size for the vise-grip in this case.

After the separation as in the photo, retraction returned to normal and was smooth and reversible. So, I just wiped them both with an octane-saturated tissue, dried, reassembled the objective, and the issue has been solved.

Finally, removal of the rear end cap was indeed unnecessary, since had I have to reach and handle the spring, it would have occurred through the front end anyway.