Just last week I went through my uncle's rig 'beer cart'. He had the exact same thing, the starter would spin but the motor would not. There is a one way starter clutch behind the flywheel. The flywheel takes a 30m 1.5 puller other then that no special tools are needed.
His one way clutch had all the teeth hanging out when I took it apart. Put a new one way in and the 'beer cart' is on the road again.