Bactron User Group  »   Sealing the airlock

I recently purchased a 1997 Bactron II, and I've found that the airlock is the source of a fairly large leak. I've already replaced the rubber gaskets, but that hasn't solved the problem. If I push on the outer door near the handle, the leak from inside the airlock stops.  Is there any way to increase the pressure on the doors? Maybe by adjusting the springs or something in the handles?

Thanks!