JLG 60H - Drive wheels STOP when turn switch is used

Hello all,
I have no experience with this type of equipment. Im all automotive and aviation.
We have a JLG 60H man lift that sat for a while. When moving the Lift and attempting to use the turn switch, it abruptly stops the 2WD wheels, resulting in a rather jarring experience.
There may be an issue with the engine not throttling up as well, according to the owner, maybe related, not sure.
I could use any assistance, as Im out of my field here.
Looks like the 3 lever controllers have been...

JLG 60H - Drive wheels STOP when turn switch is used

JLG 60H - Drive wheels STOP when turn switch is used