Hyundai gas golf cart won’t move

I have a 90s Hyundai gas golf cart (hgg1 I think) that recently stopped moving. The drive belt spins in neutral but won’t spin in forward or reverse. The drive pulley spins. I originally thought it was the belt (trying to find a replacement is tough) but I noticed it doesn’t spin faster when I give it more gas. Could it be the speed controller? Anyone have a service manual?