Originally posted by IgorZ I shouldn't have touched this... I lubricated the helicoid, but for some reason it is still stiff. Now I am having tough time putting it back together. There were to springs that stick out at 90 degree angle from the base of the rear element, and over those two springs sits the lens mount. Not sure how to put it back, especially now that I lost one of the springs! I was trying to compress it and it just flew out and got lost. And I lost infinity focus... On the positive side, now the lens focuses much closer than the original 75cm
Why did I decide to do this???
I've been in situations remarkably similar to this before now, so I can sympathise
Regarding the lost spring, the best advice I can give is to close the curtains in the room and use only a flashlight to light the floor at different angles. I've found a few lost components this way. Also, if you have any of those sticky rollers used for removing hairs from clothing, they're a good tool to sweep back and forth across the floor and pick up anything that you might not have seen.
Do you have any other old lenses you can raid for spares? Sometimes, the springs in diaphragm mechanisms can be pulled and stretched to make compression springs. I did that for an old Domiplan some time last year. Depending on the size of the spring, even one from a retractable ball-point pen might be a suitable donor part with a little work.
As I said, I haven't serviced a Primoplan before, but if you want to take some photos and PM me, I'll happily take a look and see if I can figure anything out. Beyond that, I'd recommend asking for help on MFLenses if you haven't already done so. I've had good help from those guys in the past.