If the light dims as the foot controller is used there must be a wiring problem. Normally the wires from the light go directly to the two wires on the power cord. The light is switched so it doesn't need to run any other way. If the light is dimming as the pedal is pushed then it's somehow wired to the controller.
Before doing anything else I'd check that wiring. You might have some crossed wires that could cause trouble.
I have some wiring diagrams I saved but the moderators won't let me post them here. If I do they delete my posts.
I'll send them to you if you want via email. I'd post a link to them, but I don't know where I got them. Too many computer failures have cost me a lot of data.
Joe