My first problem is I own a motor guide!

But I have a motor guide 54 lb 12 volt tolling motor that doesnt seem to be getting full power. At first full power would "kick in" after running it a few seconds but now it seems to never kick in. My little fish finder is spliced into the the wiring to the trolling motor. Could this be a factor? Or could my handle switch be bad? Appreciate any suggestions on what to check.