IH 785 clutch?

[MB Trac]

Went to look at an IH 785 tractor today. I have no experience on these unfortunately.
Tractor won't move, if you put it in gear it seems like the clutch is slipping? It wants to move but doesn't.
Do they all have the TA transmission? I looked but couldn't find a lever for it somewhere?

 

[7610 super q]

Is there a TA lever/ switch on the dash ? Or evidence that there used to be ?

 

[startinghandle]

Could be stuck in 2 gears

 

[v8willy]

They went Case in 85, then got a revamp in late 85/ early 86 when the lever changed to a switch.

That looks like a pre revamp model, but may also be an IH painted in Case colours.