It's made likely in Taiwan with 2 daylight T8 TFC branded bulbs that had tape on the ends like they used to do on those models. It took 30 minutes to remove the bulbs. One just won't burn normally. It's likely had a slow leak, and likely from the start. The other bulb is that way somewhat but once warmed up it functions. It has a dark black band that an EOL bulb starts to make, but once warmed up it is ok. The other bulb glows dimly on my solid state 40 watt ballast I now use as bulb destroyers. It isn't doing anything weird.  The fixture has seen very little use.  I right now have 2 Vitalites in it and it's purring along merrily. It doesn't glow the ends very bright when I hold the button down. Does that mean the lamps are underdriven?  I guess I eventually will have to post pictures.
The only way I got the very dim bulb to work was to put it in the microwave for about 10 seconds and it got VERY  hot and got brighter the longer it was left in, however it was VERY hot to the touch.   

Powell

The dark band on the second tube was condensed mercury, what evaporated later (as the area around electrodes run hotter then the rest). This start by a ball of mercury hit and attach to the filament. Then when you preheat the lamp, it evaporate rapidly and condense on the nearest cold surface (= tube around the filament) and so turn it gray. And then when this part heat up, it finally evaporate.
If the filament contain some bare metal parts, the mercury tend to return there after some time, as with that metal it could form an amalgam, what have slightly lower mercury vapor pressure then bare mercury.

Actually on the second bulb it appears not to be mercury as it does not go away, nor does it lighten up as the bulb operates.  It looks like some sputtering. The sockets are a pain to get bulbs in and out. I have some no name almost new daylight bulbs that have JFC as the name.  I put them in and they will stay.  They were made somewhere in Asia, but where I know not. They are very bright.  T


Powell