We've been having what looks like a big Nitrogen leak, which on the water and air check showed Nitrogen was at 3000%. We think we managed to isolate it by capping the MS and the nitrogen showing even higher abundance which suggests its to do with the MS. We only just installed a brand new o-ring in the sideplate as a recent engineer visit for a routine PM showed there was a small leak. But now after the visit the leak seems even bigger! The leak did decrease slightly after installing the new o-ring but it continues to be very high.
Any ideas of what else could be causing the issue? We tried to use Argon to detect a leak but have had no luck