Really odd Mullard GZ34!

[Tony L]

A desirable 1959 Blackburn made ‘fat base’ GZ34, but where the hell is the flashing above the dual getters? Does this imply a vacuum leak/crack somewhere? I’ve no intention of trying it as it clearly ain’t right, but I’ve never seen a valve go like this before. Any ideas?

PS I actually have access to a Avo 163 at the museum so I could test it, but I can’t really see the point as it clearly isn’t right.

 

[Barrymagrec]

When the getter on the glass goes white the valve is "soft" i.e. leaky. Do not plug it in.

 

[Arkless Electronics]

Yeah it's a dud.