SO after many months of my rear ARB not functioning I finally have a fix. I had a couple of problems going on. first of all the seal housing of the RD99 was too far out on the flange cap assembly so the seal would slip off the end and leak air. that has been fixed but the locker would still not function. So I tore it apart this weekend and compared the locker to the pictures and found some internal damage. The internals are quite simple and includes spider gears and a clutch gear that slides and locks on one of the side spider gears. The "clutch gear" and the "side gear" are supposed to mesh and allow full engagement of the locker. However the edges have "broached" or in other works ground down the edges to a 45 degree angle. that allowed the locker to engage during the bench test but not under any load since the edges were worn to a 45 degree angle instead of a straight edge. So I basically stripped the side gear and clutch gear. Parts have been ordered and I am taking pictures so I'll post them when I am done.

By the way I can see how engaging the locker while in motion would be bad for the locker. It could easily promote the "broaching" condition. NEVER engage the ARB locker while in motion!