I didn't replace the o-rings. I would check to make sure there were no leaks on the firewall side as that, I think, is where they would show a problem. If you have any questions on the removal and replace feel free to PM me.
Former owner 2003 Comp Orange Euro SVT then 2002 WRX Wagon, now 06 Magnum R/T, selling it to get another SVT Focus...
1979 Ford F-150 SWB 4x4 460/ZF 5 speed
1969 Dart GTS 340/4 speed