[Milsurplus] Smart People: Gassy Tubes Reversable?

[David Stinson]

Some otherwise valuable tubes have taken-in variable
amounts of gas over the decades.   
NOS transmitting tubes like the 211 are often gassy 
out of the box and cannot be readily "de-gassed" 
like some large Eimacs.  
Even some NOS 1625 and 807 are starting to show signs of gas.

Question:  If a batch of such tubes were put into a large
vacuum chamber, pumped-down hard and left there for 
an extended time- even a year or more- would the gas
in those tubes migrate back out?