I am working on a 1985 Hyster E30XL, EV100 traction and hydraulic controler with regen braking. The problem is The lift drive cuts out after 15 minutes of use, if while plugging you use any hydraulic function, the failure does not seem to be a PMT fault but more like a SRO, as there is no double click of the contactors. The lift seems to work fine after cycling the key, I thought the drivers might be at fault and have replaced them as well as regen contactor tips which were burnt badly. I would appreciate any help or suggestions from you folks out there. P.S. this is the early EV100, no diagnostics or led codes.