350U Starter/Starting Issues

Ok, this might get a little long. I was having trouble getting the 350U to start in ealy winter. You charge the battery up (6 volt)and the thing would only turn over 2 or 3 times slowly and then just click the solenoid. I figured the battery was shot. I decided to convert to 12 volt. I hauled it over to a buddies. He converted to 12 volts and did a bunch of other repairs. We then drove it 2 miles down the road to another shop to get painted. Everything appears to be working fine. Trucker drops the tractor off at my place to day. I hope on to fire it up and put it in the shed. Thing turns over lightning fast and instantly starts. Runs 5 secs and dies. This happens about 3 times. I figure someone must have turned off the gas. I check the fuel and its on. I go to fire it up. Just clicks the solenoid. Wont turn over. It goes from turning over fast as ever to clicking just like that. I grab the jump box. Even with the jump box it wont turn over. Clicks the solenoid and barely turns the starter. The thing that I found odd is that I left off the starter button and then 2 seconds later the starter growled a little like it was trying to turn the engine over...Ideas? Almost seams like the starter has a bad spot that draws too much current???

Painting can insulate terminals. Clean them well ground strap and all. To isolate the problem, make sure the starter motor is not jammed. High gear TA forward, rock the tractor hard, and make sure the fan is moving some. If so then try starting it again. If still nothing, tap the starter end frame with a hammer (and end grain wood (paint protection) this can reseat a worn brush for one or two starts!
If it starts, plan on putting brushes and bushings, as well as a new style drive pinion.
If no start, it is possible for either the solenoid to be sticky, or bad. If it still turns slow, feel all connections to see if any are hot! Fix those. New batteries can and do go bad! 10.5 volts while starting measured across the battery terminals is needed, JimN

check the armature also.

You have any idea what the current should be when starting? The thing that is soo odd is that the problem happened when it was a 6 volt system and now as a 12 volt. All the terminals were cleaned and reattached when we did the conversion...

Using a starter draw meter (held to the cable, not connected to wires) it should be in the area of 300 to 375 if 12v. 400 to 450 is possible on 6v.
Jumping directly to the starter lug from a 12 v battery (with the Neg terminal grounded) will isolate everything but the starter motor. Keep us informed. Jim

Charged the battery up today and now it appears to be starting normally today. Odd, but at least it appears to be back to normal...