ASV RC100 operating speed issue

Hi there, I have a ASV Rc100, that is stuck in hi speed, I'm running out of things to check and replace. so far I have done the following.
Replaced both Drive motors, checked hi/low speed solenoid & shaft, replaced all hydraulic filters, replaced all seals in hand controller. checked all electrical wires for any signs of open wires, check all fuses, and connection in fuse box.
I managed to get it running in low speed for about 5 minutes, went over a bump and i'm stuck in high speed again....

ASV RC100 operating speed issue

ASV RC100 operating speed issue