serial is AT8900790
4.3 GM pre-emissions
mast number- c70a47

the problem im having is the the lift seems very spongy
tilt and everything else seems OK
with a load it drops about 8 inches (about 20cm) slowly then stops drifting down altogether

this unit has a large accumulator mounted on the mast
im suspecting its causing the issue
anyone have any info on this esp on how to test the accumulator, i think it lost its nitrogen charge

ive seen a similar unit in a yale parts book but im not sure if its the same exact unit
couldnt find anything from cat on it

any other ideas would be helpful
thanks guys