I've posted previously about the o-rings in the Avenge-X
I was quite frustrated with mine at first and had leaks at several locations
Some of the factory o-rings were almost square and hard enough they shattered when removed.
After braving a complete tear down and replacing all the o-rings, I learned a LOT about the gun and where things go.
The only repetitive replacement has been the two o-rings in the regulator (one inside and one on the tip)
These are fortunately easy to access and relatively east to replace.
The only other significant learning was that using thin silicone oil on the regulator o-rings has been lasting a lot longer then when I tried silicone grease.
When the seals are all in good shape, my gun holds 4,300 PSI for weeks on the rack but I struggled to hold air overnight at times.