About a year ago, the electric starter on my 1997 Explorer 400 stopped working. I disassembled the necessary bits and pieces and removed the starter. When I took it apart it was full of oil. After some scrutiny I figured the counterbalance seal was shot. I replaced the seal and additionally had the contact surfaces on the commutator taken down on a lathe. New brushes were installed at this time as well. The oil was cleaned from the starter housing and commutator and also from around the stator coil, etc. When reassembled the starter worked OK for about 6 months. I removed it again, cleaned away more oil, but not as much as before, and reassembled. Now, 300 miles or so later, I have the same problem again. Has anyone else had this happen and , if so, what is the fix ?