3pt will not lower

Jinma 224–200 hrs.  Dipstick on hydro fluid has no level marks.  Ganon will raise but does not lower.  I added fluid but no change.  Former owner not available for help. 

I read about the knob below seat–no response noted.  FEL/steering work fine–trany as well.  3pt was operational–got jerky.  I park with impliments on the ground–raised so I could use fel.  Has not lowered since.

Any suggestions?  THNX, Tom

Update—-Read somewhere about a diverter knob at front of seat.  Also found another fill point under seat.  Since filling resevoir and breaking the knob adjusting valve, I have good response from 3pt lever.  Also discovered two leak points not obvious when I purchased tractor.  The volume is not great but I will check often and keep full.

New question—- What is recomended for the transfer case?  Is gear oil or hydrolic fluid preferred?

THNX, Tom