GE Spacemaker XL 1800 Struggling

Microwave heats, turntable works but sounds like the unit is struggling. Cooling fan (?) or stirrer fan (?) sounds weak. Any repair ideas? Is the unit worth fixing? [COLOR="Red"]Note: In 2007 when unit was less than 1 year old, GE technician repaired unit under warranty or recall. Did not say what was wrong.[/COLOR]