Had a similar incident a year ago, little nose smack on snow pack/ice driveway. Nothing noticeable on the I1 or Z3, but behaved poorly on yaw & roll. I personally thought it looked like the gimbal Arm was ever so slightly bent. I took it down, couldn't see a problem and created a DJI ticket and sent it in, they basically refreshed the whole camera & returned in about 10 days... I ponder if all new parts except for Z3 white housing. Worked great when returned.
Before placed it on a shelf in parts bin, I'd send it in for an evaluation & repair.
The stage you've disassembled, doesn't that require a re-calibration of the gimbal motors now? That was another reason I sent in, wasn't sure if my reassembly was as accurate as desired.
Good Luck!