snip

The original controller is stuffed, traced the
fault to (surprise) the MOSFET driver cunningly encapsulated in epoxy,
so no hope of seeing what it is. snip
This implies that you might have used the existing controller if it
hadn't failed ("is stuffed"). If so, maybe you can more easily find
another complete unit that has a good controller. Not as elegant, but
pretty simple.
Some friends of mine are currently using the "2 hp" type treadmill
motors to build 2" X 72" belt grinders for knife making.

A friend who lives several hundred miles from those guys decided to
build one too. He went to local guy who advedrtises in the local
newspaper that he will come to your house and pick up your metal scrap.
This guy says he gets a LOT of treadmills and he asked my friend how
many of that brand he wanted. I think he paid about $10 each.
This was in Rochester, MN, USA.

Pete Stanaitis