Front end loader

[HWRC]

I have a Case 1390 (David Brown engine) with a dealer installed Case 56L front end loader. The loader, both the vertical lift and the bucket angle, have begun to lower without using the levers. I need to constantly raise them during use or standing still. The three point hydraulic system holds the way it should. I cannot see any leaks anywhere. The tractor has 992 actual hours. Any suggestions on the problem would be appreciated.

 

[LPakiz]

You might try isolating the “lift” hose with an inline valve. Raise the arms, then close the valve. If it settles, one or both of the the cylinders may be bypassing internally.
If the hoses hook up with quick couplers, you could make up a test assembly consisting of a male tip, a ball valve rated at 2000WOG, and then a female coupler.