Its concerning to read all of these RA problems with the Mesu Mk2. I have the mount (received October last year.) and haven't had any of the issues fortunately.
It makes me wonder if the new clutch system of the Mk2 is part of the issue? As motor spacing is critical, I always make sure the lever is pressed firmly to lock the motor in place. Similarly for the axis clutches as any additional friction would mess things up.
Other steps I've taken include:
- Acceleration. Reducing the acceleration parameter in servo config by half which is probably very conservative. This prevents possible slip at the beginning or end of a slew.
- Balance. Ensuring its balanced in RA/DEC off the mount. I address any off-axis loads that would exceed the torque spec of 10NM (even though it appears balanced when the CW bar is vertical or horizontal). As an added check I've found if I run guiding assistant in PHD2 and I see any backlash, its likely some minor slippage is occurring - I tend to ignore this if its small and do not compensate for it in PHD2 settings. Repeating the calibration and measurement in a different part of the sky clears it so certain angles do have an impact it appears.
I used to use the dowel method described by Jonk. But now use an old Wii balance board (luckily its survived our last move!) and software I found for a project at the University of Colorado. Its much safer as I simply place the scope/accessories on the board and adjust until the COG is centred in the reticle! No more wobbling of heavy equipment while finding the fulcrum!