I have a Hustler Fastrak 54 that the blades will not engage. I was mowing in normal turf when the blades suddenly for no apparent reason stopped. It was late so quit for the day. Next day started mower and blades engaged and ran for about a minute then quit. I can't find any obstructions. The ten amp fuse is OK. When you pull the knob to engage the drive pulley does not spin. Does this mean the electric clutch is bad or am I missing something?