Is it pretty normal for stabilizers to drift down a bit/or hit line relief when holding up machine and working hoe pretty hard and pulling while extended all the way out. I was working a 310G pretty good and noticed if I had the outriggers all the way down and worked it pretty hard for about 15 min. on hot oil I could try to push them down again and they would go down, so they came up a bit. I did drift check on them and they held great. I was curious and hopped on a pretty new cat backhoe, and it did the exact same thing.
How many hours on machine??? I dont think that a mild cylinder drift is too big of a problem. Check your cylinders. If your seals are badly failed, hold cylinder fully retracted or extended. If cylinder gets very hot very fast seals are failed. The other option is do a leak test. (may be messy) (fully retract the cylinder. Remove barrol end hose, crack line first, may have pressure. Hold control to retract cylinder. If oil pours out of barrol end fitting, cylinder needs to be re-sealed. A slight amount of oil at first is normal, but should stop)
I haven't worked on a G. Do they have holding valves on the outriggers?
I'm not sure if they have holding valves. I did drift test with stabilizers holding machine 3 inches off the ground, backhoe extended fully straight out bucket 1 foot off the ground. didn't really drift at all.