is the H relay picking up for hi speed? are all the P, PP, PPP SR relays energized?
what kind of drive unit does it have? probably an SSD-1 or GFC box, could be a bad box. check your generator field voltage, should get around 80-100 volts across the generator field to give 200-240 volts output at the generator. if you are getting low generator field voltage, its either a bad box, or connection, resistor bad contact on P, PP SR etc. also have you checked the generator field fuse on the ssd unit.
i would not think about pulling the motor until you can verify that you can control the generator output with varying generator field input.
pm me with your email, i have some info on the reliable elevators, and the SSD drive unit that you may want.