Here's my scenario: I have a '49 Pony, still 6V (and I want to keep it that way). The old battery was toast so when it was picked up the seller temporarily hooked up a 12v booster and it started right up. When I got it home, I put a 12v jumper on it and it turned over but wouldn't start (not worried about that yet), but after trying for some time, the starter would no longer do anything.
Finally got my new 6v battery and put it in, but the starter still won't turn over. I can hear the solenoid clicking.
If it matters, it was hooked up as a negative ground, but my understanding is that it waould originally have been positive ground.
What is the problem and what do I do? Thanks.
 
 

Try taking a jumper cable from the battery  directly to the starter and see if it turns over.  Be careful that you make a good contection or you will get a lot of sparks.  This will let you know if you have fried your starter.  If it turns over then you will need to start from the starter backwards to find out what componet has failed.  If t does not turn over take the starter off and see that the starter is free turning.  We have a guy who will check out starter and generators in our area I am sure if you look you can find someone to check your starter out. I was having trouble with a 333 that i purchased  when  starter would not turn the tractor. over.  I  found out the motor had locked up apperently was getting antifreeze in crank case. It was not a starter issue at all.  
 

Thank you.  I will try that..  The Pony is my first tractor and I got it because it was said to be  easy to work on.  Give me a sewing machine, and I'm trained to fix it, but vehicles are not my speciality!  I'll be servicing the Pony for things like oil, filters, radiator, et. al. but  I really  don't plan on doing lots of mechanical work.