cylinder bypass ?

Is there a easy test for cylinder bypassing.....



I have a front loader bucket dump cylinder on a cat 416c backhoe (std version single cylinder) that is nice and dry but wants to dump the bucket at 70% lift height without dump control input......i suspect a bypassing issue but do not know how to test without taking the cylinder off and rebuilding it.....(4zn021xx)



any suggestions...hints...etc..



thx in advance