My high-vacuum Penning gauge has been having some problems lately. The last time that I "fixed" it, I used lead solder to create a crushable metal seal between the parts of the gauge body. Eventually the rosin leaked out and probably caused contamination within the gauge. I bought some Indium wire on eBay to replace the metal seals after cleaning the gauge with a bead blaster, sandpaper on glass, and lots of alcohol swabs. Proper explanation of Penning Gauges: http://www.thinksrs.com/downloads/PDFs/ApplicationNotes/IG1hotapp.pdf