Motor problems
I'm working on a 4hp 2 stage pump .The pump will work on low for filtration duties but when you try to operate this pump at high, a strange noise is heard for a moment and the pump will completly shut off and will now will not operate at low speed. After awhile it will come back on , but again only in low speed(filtration mode) .Prior to this trouble it would occasonally blow the 20 amp fuse on the cir board .Any thoughts?? Is it cheaper to repair pump/ or replace if this is what is actually at fault.
Any ideas who in London Ontario Canada area sells pumps at a resonable price?

Do the bearings seem to make noise or does the motor hum on high? Could be one of two things... bad high speed capacitor, or bad bearings. In extremely rare situations, the high speed winding is faulty.

Bearings dont seem to be the problem , and yes just an extremly loud
humming noise and while getting this noise pump does not engage to high speed , if left on setting high while making this noise it will cut out in about 3-5 secs and will come back with only low/filtertration speed in a bit
while on low ,no noise and everthing is fine