John Deere 8440 reverse not working

[FarmerBrad147]

I'm going to look at a well-used John Deere 8440 and the seller says the reverse doesn't always work. Probably less than 75% of the time.

Aside from linkages, what typically would be the cause of this?

Is it possibly something simple like a spool valve or some kind of external hydraulic valve?

Are we more than likely looking at having to split the tractor and dive into seals and clutch packs?

Any insight would be greatly appreciated. I am not familiar with John Deere transmissions.

 

[wore out]

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[wore out]

Reverse is totally mechanical. If a shift cable adjustment doesn't help, there's problems with the top shaft in the transmission which will require $$$ and a "split" to repair.