you starter should look something like this. If you use a long screwdriver to jump the two big terminals on the back of the solenoid, you'll run the starter. If you do that, and the starter spins good and starts the motor, it's the solenoid. If you do that, and the starter still spins like crap, slow, or doesn't spin, it's the starter.
04WJ:4.0/3"+10mm/Superwinch=DD & Expedition Jeep.