(ET) Another person with charger problems..

["Chapin, Tim" <tchapin umich edu>]

On vac. last week, I finally got a chance to mess with the e-20 that has
been setting after the purchase for over 2 year now.  The snapped off
circuit breaker still was working so I wired it in place with plastic wire
ties, pumped up the tires, put in some washer shims to take care of the
slipping steering gear and plugged in the charger.  It hummed just fine so 
I
hoped on and stuck it in ll, flipped the reverse switch and stepped on the
"gas" .  It came to life (no batteries) and moved back about 3 ft.  So I
pushed my luck and flipped it to forward and stepped on the gas.  It mover
forward, I thought, let's check out all the speeds and keep pushing the
peddle down.  Then it happened.  The buss from the charger changed to a 
very
loud rattle, the tractor stopped and about 5 sec. later the 20 amp breaker
on the plug let go.
Now if I try the charger I get the loud rattle.  I unplug it before the
breaker pops.
What did I do to the poor charger?  Any ideas?