My all tube Peavey vb-3 has a part lose. I have a show coming up this Monday. Everything is explained in this short video. Thanks for watching
Just guessing but it looks like the cover for the preamp tube just to the right of the power tubes. Again, just a guess.
It's a screening can from a B9A tube socket. Look around the amp and you'll find a pre-amp tube missing one. Ahh! Our friend from Greenville has beaten me to it.
Yes it is an easy fix, the slot and notch at the open end are a bayonet fixing that will push and turn and lock into place on the right tube socket. It will fit on one of the small preamp tubes. Have a good look and you should see one without a cover/screen but with a base with a ring with a couple of 'pips' that the loose cover will fit onto. (Hope you understand all that, very difficult putting it into words.)