A while back I posted some PHD graphs showing an issue I was having with my G11 with RA - it's still happening. It's spikes around like a large magnitude earthquake, while the DEC is a lot more refined and is no issue at all.
Admittedly the weather has stopped me from doing a lot of testing, however I've managed the following:
* Cleaned and regreased the RA and Dec gears/worms with Super Lube. This had no noticeable effect on the problem (it still needed to be done anyway).
* Tried different balance positions. I've tried slightly unbalanced in both directions and balanced. So far it seems that balanced appears to be the best, but the difference is not great enough to be truly conclusive.
* I've tried a few different orientations for drifting alignment (weights on west, east, dec at various points, most tests including the one below pointing straight up or close to it (maybe within 20 degrees?).
* I've tried adjusting the minimum move amount (lower seemed better), the hysteresis (no real effect), the aggressiveness (higher seemed better, but inconclusive at this point)
The above I did last night. With a RA peak-peak of 26.8", it's just crazy. I think I can refine the PA further to get below 1', but I doubt that should have much impact on this problem.
I don't believe this is a seeing issue as I would expect DEC to be effected just as badly then.
I have a feeling it's some form of backlash that's happening, especially since the RA is always being adjusted as it tracks across the sky. Is there a way I can specifically measure the backlash? Would it be worthwhile swapping over the DEC and RA motor, gears, worm?
Also, I'm open to any other suggestions. I'm going to go through the Gemini settings tonight (again, but with extra care) to see if anything is wrong there, but I'm doubting it. If there's something specific you think I should look at, please let me know.