That's kind of a strange problem. I would look in the forward and reverse lever switch to see if anything is broken and shorting. Those switches also have a separate circuit to turn on the steering. If the switch broke internally and shorted it may cause a problem. Also I think there are diodes in that switch housing that are in the hour meter circuit that may cause a problem if they have a short. If there are diodes try disconnecting them and see if the fuse still blows. You can also test the circuits in the reverse switch. I think there are 3 separate circuits.