Thanks for the welcome and quick reply....
Turns out that it was an issue with the motor. I had tested with 12v and it had run slowly so I assumed (always a bad thing) that it ran slow due to voltage.
I went ahead and retested using 12, 18 and 36v from the pack and it still ran very slowly.
Finally sat back and thought about it and decided to go old school. Smacked the motor a couple of times with a hammer and what do you know, picked up a lot of speed and appeared to be running well. Reconnected everything and cart is operating normally now.
As it turns out, the cart had sat for several years and it appears that there may have been some internal corrosion in the motor and the hammer did the trick.