Prototype set is here

[John Folsom]

Possible Leaks in Metal Cone portotype color CRTs

1. Evacuation seal (copper pinch off type)
2. Wire to glass seals at base (not very likely)
3. Glass to metal seal at faceplate of tube
4. Glass to metal seal between neck and rear of metal funnel
5. 8 welded bolt heads which protrude through sides of metal bell, part of the phosphor dot plate and shadow mask mounting assembly
6. Metal to metal weld between front and back of metal funnel (similar to 21AXP22)

Summary: Lots of places for these tubes to leak!