Attempting to fix the focus shitfer

Thanks to high25 from AC, for the Silicone lubricant, I decided I'd have a regrease of the focuser and see if I could do anything about the image shift when I try to focus. Ok, first off, remove the focuser from the OTA, figured this was a good idea, as I didn't want to get anything on the lens. I promptly dropped the first fitting screw for the focuser and looked on helplessly as it bounced and rolled under the cupboard, I really should have had a tray or something underneath, 20x20 hindsight is a wonderful thing. Anyway, after judicious use of various tools, implements and torches I did, thankfully manage to retrieve it. I moved away from where I was and put something underneath to catch anything else I might drop.

Once all was dismantled, I managed to clean all the greyish gunk that felt more like superglue than lube that was all over the focuser with application of cloth, toothbrush and wd40. Of course it got everywhere and I spent the next few minutes trying to wash this stuff off. Then using a bradawl I applied the silicon stuff and had a look to see if I could work out what was causing the image shift.

By a process of experimentation, I narrowed it down to a slight shift in the drawtube when the focus knob is turned in the opposite direction from previously (Backlash??). I applied strips of sticky back plastic along the drawtube where the felt runners are in the focuser itself. Not enough. What else can I do ? I added a piece of cardboard, folded several times and a spot of glue to hold it in place under the gear at the front of the drawtube. All these steps appear to have helped somewhat, but I won't really know by how much until I can test it out properly, oh and the focuser is much smoother to use to now.