John Deere 316 has reverse but no forward drive

Hi Fellas,
I have an old 316 that sat outside for a few years It's a good runner but something happened apparently from lack of use.
I had to replace the starter and carburetor to get her running but now the tractor will not go forward but works fine in reverse. FYI I did turn the (freewheel) knob in all the way before I put it away, and it had some loss of power when going up a steep grade back when it was working.

any suggestions would be much appreciated!

Thanks