I needed to work on a Rokkor lens (58mm f1:1.4)that I recently acquired with a body that I really wanted. The focus ring would not turn nor did the aperture work. When the lens came apart I saw that someone had once been in here. All the pins and tangs to connect up the aperture had disconnected along with the metal shaft used to connect the rear helicoid ring to the front helicoid ring as a unit.
Taking care of the aperture was a simple process and it now works fine. Took awhile to even get the two halves of the helicoid ring together so the shaft lined up with it's slot. Check the ability of the focus ring to turn and not disconnect. No problem there however infinity was off just so slightly. Almost like one thread on the front helicoid section.
This is where I have been stumped. Every time I move that section one thread the shaft and slot no longer line up in order to insert them and maintain alignment for the aperture pins and tangs. Since I have no clue what the original measurements, like front lens back to the mounting base are, I am stumped in how to magically find the place where it all falls together.
How do you know infinity focus is off? It could be that your focus screen is out of alignment. If film tests confirm that it is off, you should be able to ajust the infinity focus by loosening adjusting screws in the front of the lens (under the name ring). These screws determine the position of the infinity focus stop.
