2000 Bombardier will not go

[Theocat0]

I will describe symptoms:
When I turn key it clicks as it normally did and wants to engage (sometimes will go a few feet). Originally I suspected that the aux battery was low on power as I assumed there must be a solenoid that wasn't engaging...and charging it up always seems to rectify the problem (the on board charger for some reason doesn't charge this battery and I haven't dropped the pan to find out why). But progressively this was not working until the cart just doesn't not go. Sometimes it would take a few seconds for the cart to engage going from reverse to forward.
I suspect the solenoid (if there is one?)