I'm reviving this thread as it's the closest I've found to my situation, and haven't quite found a solution anywhere else on the forum.
Basically, I'm having the classic "is my gimbal centered?" issue, but I think my issue may be because of slop rather than it not being calibrated correctly.
What is happening: When pointed perpendicular to the handle, I can balance the sled perfectly. If I rotate it 90 or 180 degrees, as described in the U2 manual, it's out of whack. From the camera's perspective, it tilts forward and yaws toward the handle. The odd thing is that after adjustments, it always tilts forward regardless of where it's pointed. Since it tilts in both directions on the axis, this makes me think it's slop in the bearing rather than misalignment, which I expect would tilt it in the same direction regardless of which was the sled was pointing.
What I've done about it: To start, this is a Flyer LE gimbal, so maybe it just has looser bearings than the big boys. I took handle off the yoke, and the yoke bearing feels tight and correctly adjusted. I removed the yoke from the pan bearing and tested the two tilt bearings, and they felt good. While mostly disassembled, I felt the large pan bearing and it feels like it has was slop. It looked like it was a cage bearing set into a race and retained rather than a sealed bearing, and didn't seem like there was a way to tighten it. After reassembly, I could feel and barely hear the slop coming from the pan bearing. I retightened everything I had the means to get at, short of the circlip holding the pan bearing in.
Long explanation I know, but hopefully enough that someone might recognize my issue. Any thoughts on if the pan bearing is the cause, or if it's a different bearing or something entirely else? And if all else fails, any recommendations on who to send it off to, Tiffen included?
Thanks so much for your help on this and for the best forum on the internet!