Been there, and had the wiring chewed up on my JD420 2-cyl tractor and JD110. Repaired the wiring and scrubbed the whole mess out of there, only to have the mice move back in within days. I could hardly stand the smell of the urine and feces, so after cleaning it again, I sprayed it down with bleach to get rid of the smell. Interesting enough, the mice didn't come back to either tractor. I don't know if it was the smell of the bleach they didn't like, or the possibility that they couldn't smell their old tracks. I since have also used this method (bleach) on my wood deck, after the raccoons crapped on it, and have found that they do not come back to that spot. Again, is it just chance, or does the bleach work. I am tempted to extend the bleach treatment to my woodpile where the raccoons have a heyday crapping on the wood. What a disgusting mess. I shoot them when I have a chance, and trap them too, but don't like the chore of getting rid of the carcasses (35-40 two years in a row!). I don't mind the raccoons, as long as they change their waste disposal habits.