Yamaha G16 36V Jerks but won't move

[tkamleiter]

I have a 2002 Yamaha G16. This thing continues to give me trouble.
Earlier this year my daughter and a couple friends got it stuck in mud. They pushed it out while running it at full power. It ran for a while after that then it just stopped. When you pushed in the gas it would jerk but not move forward. I assumed the batteries were bad so we pushed it to the garage. It rolls free. I charged the batteries and they got to 36 volts but not much past so I ordered new Trojan batteries. They came in a couple days ago and I put them in and charged them. When I hit the gas I get the same thing. It jerks but won't roll. I jacked the cart up. When I push the accelerator pedal the passenger side wheel rolls free but not to full speed. The driver side wheel jerks. Both wheels spin free by hand. No weird noises. No rubbing. No noise from the axle.
Any suggestions?

Thanks,
Tim