I visited CVR's website, and it looks like they are using a Nippon-Denso starter as a base, and then providing a bunch of different adapter plates.
Nippon-Denso starters are very good overall, but their weak point was always the solenoid contacts, which are usually available seperately from nearly any electrical rebuilder.
is for the ProTorque / ND19750 for the Protorque Maximum.
My bet is that these copper contacts have been arcing (Do you ever get the click but no crank ... click ... click ... crank scenario?)
What will happen on occasion is that the contacts will arc and fuse together, which causes the condition that you describe.