"He who marches out of step hears another drum." ~ Ken Kesey
@ Paul oil was the first thing I checked looks fine, @ Bink, no it starts fine running normal speed then later in the day it kicks on and runs slow and yes it's single phase...brand is AMP (Air Moving Products) I've had this unit for 6 years now.Darryl
Generally speaking it doesn't pay to check and or repair a motor under 10hp. If you can change the capacitor and maybe bearings yourself its worth it but beyond that throw it out and pick up a new one.