Hi Edward.T,

I have no information on this Ser,no looking at the spec checker this truck appears to be a electric pallet truck mover and dose not appear to be a Yale I am familiar with, dose it have a ride on platform or a mast, or guards to support you on the platform as you ride, if it has these I would sugest you check the sensors on these parts as any failure in those components will put the truck into a permanent slow mode but Im sure you know that , I don't think you specified the fault codes displayed maybe you can do that and I may be able look info out on the fault codes.

Titus