1. Disassembly
The Industar 10 requires very little maintenance and is easy to repair. Of course, after decades of use, the lubricant has hardened or even disappeared completely and needs to be replaced.
Loosen the two limiting screws and unscrew the lens from its thread.
Pay attention to where it comes out of the thread and make a good note of it! It must be screwed back into the thread at exactly the same point later.
Here, it was between 2.5 and 3 m, but it can also occur in completely different places. Therefore, the ring with the meter scale cannot be screwed onto another lens, as depending on the entry point of the focus screw, it may not be possible to turn it to the infinity mark or it may not focus properly.
2. Cleaning
Scrape the old gunk out of the threads. A toothpick or (with a little care) a small screwdriver is suitable for this.
Then remove the residue with spirit and a toothbrush, for example, and wipe everything well. You can get your fingers quite dirty, so wash your hands before reassembling.
If necessary, the lens can be completely disassembled relatively easily, e.g. to clean fogged lenses. The front lens is held in place by a threaded ring, the rear lens block can be unscrewed after removing the jammed ring (bend the 3 tabs slightly forwards with a screwdriver).
3. Lubrication
For relubrication, a grease should be selected that is temperature-resistant and does not start to run when heated. An inexpensive grease that meets the requirements is available from Atlantic, for example.
You don't need very much, about three times the amount shown at the top of the screwdriver is sufficient for the entire thread.
Spread the grease evenly, screw the lens back in at the correct position (which you have hopefully made a note of), insert the two limiting screws - done!