Westinghouse 22 inch color restoration

[old_tv_nut]

What video had you been running when the purity "popped" and what did you then run until it popped back? If it is the shadow mask, it seems like it must be some really sudden movement due to thermal expansion and "oil-canning." This is the first I have heard of a tube popping out of purity suddenly. Usually overheating causes "doming", a gradual loss of purity in a bright area like the white patch on composite color bars.