Help with convertible lift system

Just sent my switch in for a second rebuild(5 years since first rebuild).this is his response "What I want you to see it the amount of arcing occurring. This switch is really getting hot while in operation. I would inspect the wiring terminals on the switch and motor side. I believe there is something causing a restriction of the DC current.". What do I check? Is there some tests I can do to the motor? When going up or down it does kind of stop for a split second. I do have a relay kit coming.
Thanks
Aaron