C3G case removal - preamp tube
Hi chaps,
how would one go about removing the protective casing of these C3G tubes?

My DAC only accepts the 'naked' tube without it's protective case.
Doesn't seem to twist much (don't want to force it) but there is a ridge with a slight lip where I assume the top separates from the bottom.
Gently heating it? A flat-head screw driver? Rubberised pliers?
They ain't that cheap so don't want to damage them!
Cheers
Chris
System 1: - Amp - Musical Paradise MP-701 mk2 - Neurochrome 686
- Source: Audio Technica LP-5 - Custom 6V6 stage - Novafidelity X30 - Soekris 1421 (LPSU) - Custom TDA1541 C3G DAC -
- Speakers: Martin Logan Prodigy's - Subs: - REL T3's -
System 2 - Amp: Musical Paradise MP 303/Custom 300B SET - Custom 6SL7 Pre -
- Source: Pioneer N-30K - SONCOZ SGD1 -
- Speakers: Loth X BS1's - Sub: REL T3 -