Hi Bob, I've owned a number of DAQ's and have had some leaks. It's been a few years since I worked on one but on mine, the problems were all at the piece the Foster probe screws into, the into the pressure tube. Here, Dennis uses teflon plumber's tape and if tape is not wrapped properly it can cause a leak, usually pretty slowly, over a day or so.
Clear ALL pressure from the gun, dry fire to be sure it is empty. Take off the barrel band, then barrel, and unscrew the end piece that holds the Foster's fitting. You can maybe use a pipe strap or pipe wrench, if you are super careful to keep from marring the piece. I made up a wooden block to hold the piece that fits snugly around the piece and has screws to tighten enough to hold it as I unscrew it I use a turn of masking tape on the piece to protect the finish. Clean the old tape away, clean the threads, and re-wrap the plumber's tape, maybe 3 turns, be sure to wrap it in the proper direction so it won't unwrap and bind up as you screw the piece back in. All the DAQ's I've had that leaked, this fixed them. Pretty simple fix, overall. Let me know if this helps. I'll be at the Hickory Airgun show in October.
Evan from NC
