3-Point Hitch 790 3-point will not go down without extreme force

[markcg2000]

I have a mid-mount mower. Last week I noticed it wouldn't lower. I got off the tractor and was able to push it down. Kept having to do that. The level set lever moves easily, the arms came up quickly. Took it in the barn and pulled the mower to see if something bent/jammed. Nope; looks fine. Without that weight I cannot get the arms down at all.
The rate adjustment is set all the way to Fast. I moved it around but that made no difference. The power steering and the hydraulic top-link operate just fine.

 

[Tx Jim]

I think either the rate of drop valve or control valve is not operating correctly. I'd start diagnostics by removing R-O-D valve for visual inspection.

 

[markcg2000]

I think either the rate of drop valve or control valve is not operating correctly. I'd start diagnostics by removing R-O-D valve for visual inspection.

Yeah. that was where I was headed if no one had an easier idea