JD 401C shuttle shift problem

[tjtulsa71]

I'm having a problem with the shuttle shift not working in forward or reverse in higher gears. As you go down in gears it will start to move the tractor but then it stops, higher RPM's doesn't seem to matter. I don't know anything about the internals of the transmission or the hydraulics but it's acting like the clutch isn't releasing. Any ideas on what the problem could be and how to fix it?
Thanks.

 

[Tx Jim]

:welcome: to TBN
How long since hyd filters were changed & sump screen checked/cleaned? If no very recently then that would be the 1st things I'd recommend to do. Sump screen(parts key 15) can be accessed on RH side of trans housing retained in case by a fitting with a hose attached.

 

[tjtulsa71]

I changed the filters but that didn't help. I'll check the sump screen.
Thank you Sir.