if your starter soleniod is sticking, sometimes you can it going again by hitting it with a hammer. Take care not to hit the terminals or other delicate parts.
Another thing to try is to send a + feed from your battery and send touch it on your solenoid terminal. If the starter kicks in then you have a wiring fault between your starter and your key switch.
I wouldnt recomend trying to fix the starter yourself, we always send them away to specialists to repair as they are very tricky things to fix without specialist tools. You may have a specialst local to you who will be able to recondition your starter.
alfie jcb/bobcat tecnician uk, November 2009