How do I solve high oxygen and nitrogen levels after a gas cannister change?

Question

After changing to a new gas cannister, I have been chasing high Oxygen and Nitrogen levels in my system. The gas filters for both instruments show they are still fresh (the right colour indicator), I've switched out for another new gas tank, purged the regulator, tightened fittings and wiped down the analyzer chamber seal. How can these levels still persist? 
 My triple quad and single quad systems are hooked up to the same He tank. The triple quad has O2 levels at around 7% and N2 levels at around 25%, the single quad has O2 levels at around 3% and N2 levels at around 15%. After each of the above troubleshooting attempts, the levels are the exact same, no real change. Since they are close to atmospheric levels, I thought maybe an air leak, however, the H2O levels are below 1%. 
 Any help is appreciated. 
 K

Coast123 · Answer

I did a soap and water test on the regulator connection to the tank, and it showed some leakage (disconnected from the instruments of course). I retightened the fitting with some plumbers tape and the leak is sealed. It appears to have fixed the N2:O2 levels in the single quad.

For the triple quad, I noticed the levels of N2:O2 would decrease if I increased inlet flow. I replaced the consumables around the inlet, and also double checked my glass connector between my column and my guard column. The appeared a little loose, and so I tightened that and my O2 levels are now below 1%. I wonder if it came loose during the gas purge, or when I was playing with the column connection.