In your third photo notice the two (2) small holes on top. In each of those holes you will find a recessed metric set screw. Carefully tighten or loosen each set screw to further remove any focuser tube "play". Metric Allen Key Size: 1.5mm (typically). Before adjusting these set screws apply a drop of light oil in each hole.
I have reworked numerous Celestron, Orion and Skywatcher rack and pinion focusers.. They are all basically the same. 1.25 inch, 2 inch, refractor, reflector. Too many to remember. Probably not 100 but maybe. A few thoughts:
- The critical step is to adjust those set screws before installing the pinion gear. You want it to be free of unwanted play but smooth and easy to move by hand. As they come from the factory, these focusers are nearly always stiff but also shift because these little screws not properly adjusted.
- The next step is to install the pinion assembly. I take time in adjusting the preload on the pinion so there is a minimum of backlash in the gear but the action is still easy. Tightening the 4 screws until they bottom out results in an overly stiff focuser. I get the adjustment right and when I am happy with it out in the field, I will put a drop of crazy glue next to each screw head to lock it in place.
- If I use any grease at all, it is minimal, the pinion shaft and spring where it contacts the pinion shaft and occasionally I will lightly lube the drawtube but wipe it off before installation. There is way too much grease in the photos.
Grease and optics don't mix. Invariably you will get the grease from the drawtube on your hands and it will find it's way to the eyepiece.
- I just did an old Synta 120mm F/8.3 focuser yesterday. To really make the focuser tight but smooth and easy, I replace the polymer strips with 0.015" bondable Teflon. One side of the Teflon is etched so it can be glued.
You can see the strips in this photo:
I just peel them off. Sand the surface of the focuser to ensure a good bond. I cut the strips about 0.60" wide and 3.0" long. I just use "Crazy Glue Gel", spread out the glue on the etched surface, place the Teflon on the focuser and then use the drawtube with hand pressure to ensure a good bond. Make sure the Teflon strip doesn't shift when installing the drawtube. I do them one at a time.
After about 5 minutes, I install the drawtube with the upper lock block, no grease. I adjust the two small set screws for the proper feel, smooth, light and no free play. I then install the pinion as described above.
I usually remove the focuser from the scope to avoid losing the upper focuser pad. So I will reinstall the focuser, and I am done.
With the Teflon, the focuser is much lighter and very smooth. It's not quite up the standard of my TeleVue rack and pinion focuser but it's surprisingly close. I was getting real time focusing at 500x, no trial and error required.
I purchased the Teflon from Amazon. It's a 6"x6"sheet. Make sure you get the 0.015".