Belarus 250as lift problems

[roofmonster]

I have a Belarus 250as
My 3-point stopped lifting.
The hydraulic reservoir is full and fluid pumps freely out of the bypass valve in the hydraulic distributor, I took off the hydraulic pump inspection plate and the pump is engaged, the lift cylinder only moves up about an but inch you can manually pull the lift up without an implement on when the lift distributor is engaged.
The hydraulic pump is engine drivin, has a fluid check plug but no fill plug?
Any advice?

 

[Norm W]

If the other hydraulics work OK then this probably isn't the problem, however if there is nothing else on the tractor but the 3-point, then I would check the relief valve to see if it is stuck open.

 

[roofmonster]

Yes sir, nothing but the three point...Where is the relief valve?

 

[Boris250]

Hydraulic pump check plug is also the fill point. Periodicly drain the pump then refill with the same hydraulic oil in the rest of the system (about 4 oz). I use an oiler with a flexible spout, available at most any hardware or tractor store.