I've worked on several of these, but I'll be dipped if I can remember for sure, but I believe that the resistors will be in series with the windings.

Maybe this would be a good time to contact the manufacturer & obtain a wiring diagram, which would be handy to have in any case.

Maybe it is time for a VFD. I wired a double bridge system with 4 hoists last year that had VFD's on the bridges, the trolley & the hoists. Talk about sweet. No jerking, both bridges & all 4 hoists moved at exactly the same speed.

Few things are harder to put up with than the annoyance of a good example.