[R-390] Tubes new or used?

[charles bolland]

I was wondering about the 3TF7 ballast tubes.  When I purchase a tube from a
tube vendor or other source,  will I ever receive a new tube or have all the
existing tube been used at one time or another?  My currecnt 3tf7 blew this
morning.  I have a spare, but I don't want it to die on me, so I saving it
and using the resistor again.   So, do you think I'd ever find an un-used
3tf7?

Chuck