Short of outright replacing the CRT with one of the
same type, is that
still accepted practice - or in the years since has someone worked out a
way of applying new sealant across the entire face without getting air
trapped in there, thereby maintaining the structural integrity of the original?
The antique TV guys I know generally let the protective shield float
over the CRT with no sealant. Generally they will just support (if
even needed) the shield with four dabs of silicone or even just four
little bits of double sided foam tape.
Those shields really are not needed, except to maintain "the look".
Large CRTs have had fantastically strong faces since mid World War 2.
Go find a weak ca. 1949 10BP4 (and that is "pre-banding"!) and break
it - you will find out just how strong those faces are.
--
Will