Zenith Porthole CRT info needed

[ohohyodafarted]

I have a 12" zenith porthole with a 12up4 metal shell crt. I sent it off to Hawkeye to be rebuilt but Scott is reluctant to do it because of a very high failure rate on metal shell crts.

A while back I read an article somewhere about someone who substituted an all glass crt in place of the metal shell crt in a Zenith porthole but I cant locate the article on the internet anymore.

Does anyone rmember that article and have a link to it?

Thanks,
Bob Galanter