Engine won't start, just get occassional clicking from switches in fuse box, which I have replaced. Starter motor and battery are okay, won't even jump start - any suggestions?

Connect a test lamp to the starter solenoid and see if it comes on every time when the switch is operated, if not I'd suspect the switch on the end of the ignition barrel.

first thing is to check volts (in the starter motor ofcourse) if there is good electricity, then the starter motor is sutck, it happens when dust and dirt get to clocked up there