Many thanks, Marc! Now, where did I put my Sencore 7000? 😕

I'll pass this on to Simon, see if he thinks it's possible and whether he has the tools - if this works this could be a very useful procedure, as you say, there are many sick and dying Avant's out there and it would be nice to be able to expand their lifespans. It's either this, or find out whether there is any other tube (eg Philips) that can be used to replace it.

Don't forget.... this takes a certain "feel" to do, as well as knowing what the particular tube type can take.

As to replacements, similar tubes can be swapped.  I do this a lot.  They have to be in the same family, but it's also possible to

make a custom socket adaptor if the pins are different.  The basic voltages need to be close to avoid modifications to the set itself.

A good "old school" tv guy should be able to do all this.  Pity that modern techs are mostly board swappers.  

Yes, you can heat and tap it as well.  But not too hard.....

Some people face the tube down, the theory being that any contaminant will fall harmlessly into the bell.  However, between the cathode and the front of the tube is still the entire electron gun structure, so this probably doesn't actually work.  I never do this.  I shoot tubes with the back off the set sitting normally on my bench.  Worked fine for 20 years.  The only difference is that I have modified my procedures over the years to reclaim heater to cathode shorts which "cannot" be removed by zapping it.  (A high current discharge between the cathode and filament WILL burn away the short, but blow open the filament at the same time.)  Anyhow, you have nothing to loose.  In cases where a CRT is still "OK" but a bit soft, I refuse to shoot it.  Since it's still entirely watchable, the risk is too high.  But if it's really hosed..... sky's the limit.

Marc