Hello FredMan
I didn't want to answer this, because I don't really know the answer, but since no one else is replying, I'll do it anyway.
This shouldn't happen. I've used JJs in various positions in my 2x12 deville without this happening, including, I think, the ECC83S. At the moment I have one in V2 (I think).
The definitive site for Hot Rods is
http://studentweb.eku.edu/justin_holton/I couldn't find anything like your problem (see "miscellaneous problems").
Seem to be a lot of problems with the screen resistors, though, which could cause glowing plates..
If you are comfortable working on a live amp, check your bias. If you are not comfortable working on a live amp, take it to a good tech. If you aren't sure if you are comfortable, take it to a tech. There are lethal voltages in there (485V) and you have to get close to them to check the bias.
steven