Actually, sometimes 40% seems to be okay, other times it shows my problem, and still other times, it shows the problem about halfway.

In the latter case, some of the off columns are lit and others are not, usually in clusters. Sometimes some of the columns flicker and some are lit. Sometimes all of the affected columns flicker.

There's obviously some threshold problem.

Also, there now seems to be no difference in brightness beween the 70%, 80%, 90%, and 100% settings. This may explain the perceived dimness this morning.

Okay. More information. Sometimes, and I have no idea what defines those times, the screen, when normally in a brightness area that would show both sets of columns, will ghost, as if it's having bad OTA reception. It's hard to make out exactly what's going on, and I haven't caught it at a time when I can take a picture, but it appears that the always-on columns are being repeated in the sometimes-on columns to the left, opnly dimmer. I want to say that when this happens that the sometimes-on columns are also showing the correct thing in addition to the ghost.

This really sounds like a defective VFD, I'm afraid.

I'd be happy to replace it, but if it is a defective VFD, then it's the second one I've had that's defective in that unit. I don't want to put another one in and have it burn out, too.