Please Help!
I have a Toyota 7 series diesel forklift.
Problem:
Unloaded, the boom goes up and down without any problem.
Loaded, the boom sometimes gets STUCK UP, and does not go down.
- when try to lower it, the chains fold down but the boom stays. Then maybe because of gravity, the boom suddenly drops until the chains become straight. very dangerous..
- handling heavy objects, it sometimes works. i pressume gravity forces the boom to go down? it gets stuck more handling lighter objects..

Nothing is blocking the way of the mast.
I topped up on the hydraulic oil.
No visible leaks of hydraulic oil.
The load that I handle is not exceeding the capacity of the forklift.
No indicators on the panel lights up.

Thanks in advance..