Roksan 20plus motor issue

The motor is will run for 10 - 20 minutes & then stop. I have to turn off the speed control & then on again & it will run for around the same duration. Any ideas as to why this is happening...?

The head engineer at Roksan isn't available until Monday so in the meantime I thought I would ask you guys...

Plug your TT into an outlet directly and see if the problem still happens
I'll try it thanks.

It's currently plugged into my Nordost Thor...
Tried it & still the same.
I can't figure out what is happening...