On Tuesday, January 17, 2012 4:30:39 PM UTC-8, mathog wrote:
Samuel M. Goldwasser wrote:

1135Ps are available surplus in
excellent working condition for a small fraction of the new price.

Where? The ones I have seen on ebay are pretty iffy

I think you're right to be skeptical of used items, in this case.
The gas laser, a HeNe type, depends on the correct gas
mixture, and the helium will, with time, diffuse out of the envelope.

Buy a new part, if you can.

In related news, all the common CF fluorescent globe-bulb
replacements use a small bit of radioactive material to get 'em
started: don't stockpile those lamps, because the half-life of
that item is only a decade or so. For infrequently used lights
(attic, crawlspace, guestroom closets) you'll get better service
from incandescents.