Taylor Dunn B Rheostat Speed Control Sparking

[WoodMerc]

Hey all, new here and a gal, so don't hold that against me. I know quite a bit about what I'm doing. Bot a B-Series used at an auction and fixxed the F/R switch so it goes now. However, it is real jerky when you start up and the rheostat bars (may not be right term) sparks. I don't think it's supposed to and we filed a place on the bar the j-hook runs on down so the pedal is smooth. I'm thinking maybe it's not adjusted correctly or I've got something touching but I can't find it. Just looking for some common sense help here. Otherwise it runs great. Just hate to cause more problems down the road. Can't seem to find any help anywhere else.

Thanks for your help and don't be thinking it's funny to steer me the wrong way!