David,
Could be lots of things wrong here but my first guess would be a worn out trigger switch due to a happy trigger finger. I have seen alot of folks run hedge trimmers, gas and electric, with a constant on-off goosing, so those 60 hours could add up to a lifetime of trigger pulls if you are in the club. The fix is to take it apart and bypass the trigger switch with a jumper wire and carefully plug it in and see if she goes. If so, find a new switch and you are set. If you can't locate one get creative and find a spot to drill a hole and mount a standard push button you can hold down with a finger. Avoid leaving it hot wired (jumpered) or swapping in a toggle switch. Lots of club members have lost their heads going down that road. My next guess would be brushes or brush springs or a dirty armature, but once inside you can have a look.
Tom
September 2008