7jp4
 

Got a set that has a 7jp4 in it but to get a decent pic I have to lower the brightness otherwise the screen is really bright when the bright is raised up but no picture can be seen just really bright blank screen. Would this be an indication the the tube is weak or gassy or a fault with the set its in. Because there are a lot of theory's out there about how a 7 jp4 behaves when it's going bad or not so just trying to figure what's what.

The image tends to go negative looking at higher brightness when they are weak.