(ET) I5 reverse only, no forward

[Charlie <medievalist gmail com>]

Hi All

  I've had an intermittent problem with the I5 for about five years
now.  I've got the very last version of the electronics, no edge
connectors, no transistors.

  To try to solve it, one by one I have replaced all the contactors
(yes, ALL of them) and rebuilt all the open frame relays.  Each time I
replaced something, it would start working perfectly... for a little
while, but then it would start acting up again a few weeks later.

  Basically, when I go into reverse, sometimes it won't go forwards
again.  I can pound on various parts of the tractor, or switch it back
into reverse a few times, and sometimes the problem goes away.
Sometimes it does not go away until I replace a contactor or a relay
or something, then it'll work for a while.

  It's occasionally been stuck in reverse for a week or two, and I've
had to cut an acre of grass in reverse...  not much fun with a foot
throttle and a front deck.

  Do any of you have any suggestions for where to look next?  I
cleaned and tightened up the big molex connectors already (and that
fixed it for almost a week).

--Charlie
1973 GE I5 Elec-trak