Samuel M. Goldwasser wrote:


This ia an SP-120, probably from the 1970s. And, yes, those old tubes
do leak due to the Epoxy seals. Modern tubes do not leak.
I hate to dispute a known expert in the field, but as you say
this laser may be almost FORTY years old! Yes, the crummy old tubes with
sloppy epoxy seals may have leaked down in a few years, but even the
best HeNe all-glass tubes will eventually lose their He. It diffuses
right through the glass. And, the partially aluminum tubes
leaked much faster, still.

Jon