I have an '04 G7 also. Is it "EQ Systems" ? You can find their web site and put in a help request. I have a similar issue with "bypassing" cylinders. They cannot be rebuilt but are still available to purchase. THis is what their support told me:
Sounds like we have some possibly bypassing cylinders.
All retract the system
Remove top hose and fitting from suspected jack
Hit all retract again
While going through the second all retract sequence, if there is any fluid coming out of the top port, that jack is bypassing.
https://eqsystems.us/eq-systems-serv...ing-documents/