We recently had to take the top of the drive unit apart down to the upper bearing to replace two felt seals that are located just under the thrust plate. Prior to doing so we had no issues other than the thrust plate was loose. While doing this we discovered that the steer motor needed attention, and we ended up replacing this as well. Prior to taking off all wiring we made sure to label any that we could possibly get confused/hook up wrong.
After putting everything back together we went to take the lift out of the shop and as soon as the FS/RS switch was engaged the drive unit started to shake. This would stop, but only when you twisted the throttle fully one way. We checked the wiring going to the top of the motor and the brake. Then we check the three cables from access 3 to the motor. All of those checked out good and none of them have any nicks/cuts. I did find that when calling for power you go from having 26-27 volts at the cables (motor or access 3 side) when at rest to 12-13 volts. This drop starts at access 3 and the power going into the access remains constant.
We did try a new access 3, but this did not solve the issue. At this point we are lost on what to do from here and was hoping for some guidance.

Thanks in advance