Assuming your mount drive parameters are right, have you ruled out weight balance as an issue? Some mounts are pretty difficult to achieve correct balance by just loosening clutches and watching scope moves during setup. If not right, it will definitely show during calibration. If you're not sure, I suggest the following:

Let's say for discussion purposes you are imaging in the east (weights on the east side of pier/tripod). If you can't get RA reverse calibration to behave, it might imply you have too much west weight (i.e. you need to move weights down a bit on the shaft). If you are struggling while imaging west (weights on west side), it would mean you need to slide weights up the shaft. The amount to move is subtle and specific to your gear. If you want to experiment, don't get carried away. Try to remember where you started, make small weight adjustment(s) on the shaft, and then test calibration again. If balance is the issue, you'll notice that responses (how far each calibration step gets) will change. You might have less distance response in forward RA, but start picking up reverse motion that you don't currently have. With a couple of tests, you should get a good feel for weight sensitivity on calibration. In the end, the balance goal should be very slightly east heavy (keeps a load on the drive while minimizing oscillation). This trick works for RA and DEC. Anyway, something easy to try as you continue debugging. Good luck!

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