Originally Posted by rcmustang
Could be a bad power connection, ie: positive/negative battery cable, dirty batt terminal, corrosion in the cables, etc.
x2 IMHO…, try easy stuff first.
Clean the power connections and the battery connections.
Not sure but if there is a separate solenoid make sure the mounting is grounded to bare metal.
Another thing that help the starter… run a separate ground wire from the negative battery terminal to one of the starter mounting bolts, clean the area where the lug will mount and use some Dielectric Grease.
The extra ground cable will help for all electrical components, increases/improves the negative path.