[La Mouche]

For the past few months, the wiper fuse (#5 - 15 amps) keeps blowing. At first, I thought it was the linkage that was seizing up, I took the motor out, checked the linkage, it works fine. I greased the fittings anyway, wipers worked for about 4 days without changing the fuse. Then the fuse blew, I thought it was the windshield washer pump, disconnected it, it worked for a few days, then the fuse blew again.
I thought that it was water getting on contacts, put some dielectric grease on contacts to protect from water, even covered motor with plastic bag to make sure no water gets on it. The motor worked no problem for about 5 days.
Sitting at a store waiting for my wife, the car was running, I heard a pop, tried the wipers, the fuse had just blown again. I did not touch anything.

Now I am baffled. What could be the cause for my wiper fuse to keep blowing? If it would be a short circuit, the fuse would blow everytime? If it would be the motor, the fuse would blow only when turning on wipers?
Please help me.
p.s.: sorry for the long post, new at this.