The mount in subject is the venerable NEQ6. I had some discussion about this mount here CN, but now I have decided to just bite the bullet and do a tune up as it was not performing optimally anymore.
I was following the video tutorial from DeepSpace Products (thanks Ed). It is very thorough and easy to follow. So far the NEQ6 is almost completely apart. My main idea was to regrease, replace the 4 worm gear bearings to SKF ones, DIY altitude adjustment and adjust the entire system to top performance.
So far so good, although I had some unexpected issues. On the large tapered bearing located at the bottom of the RA axes, there are 3 small retaining screws, one 2 of them was Philips screw and easy to remove, while one (the bottom one) was a Robertson and it was full of some sort of dirt that I had to dig out from the head of the screw. I bought this mount new so I don't know what this was.
Furthermore, although I was not planning to replace the 6 main shaft bearings (3 on each shaft), 3 of them is bad, one from the DEC axes is really bad. It binds, difficult to turn and it also makes some suttle noise. So, I think I will replace all 6 of them, might as well. Chances are that if 3 is gone from the 6, the other 3 will follow shortly.
I did not take the motors out yet, but I could check the gears and there is a very visible/hearable backlash on both axes, especially on the DEC axes. I will update as I continue the disassembly. Any suggestions are welcome...