Loader John Deere 260 skid steer steering issues

[Jrosetx7]

John Deere 260 skid steer. On the right side steering the wheels turn at a slower rate than the left side. If no load you can compensate by letting off on the left side a little to match but with a load there is no power and they slow down even more so you just go in a circle. Any ideas on what to check?

 

[Rustyiron]

That's a fairly old model and might just be a linkage adjustment under the seat. Tilt the cab and the linkage will be obvious.