my mom's dad and step-mom have a F32T8 (well, i know it's T8...) manual preheat light built into their stove just above all the knobs. it's an alto from 2011 and is used every night as a nightlight and has NO blackening on it at all! pretty good for dusk to dawn use for two years so far!
I think it might have been one of those 30" or 28" T8 lamps. I have a few of those I got for cheap at a hardware place...they're blackender Philips lamps. My stove uses the 28" 18w T8s.
maybe it is... I didn't remove the lamp since it looks pretty dificult to remove, as the opening is just a hair larger than the lamp itself so you can't grab it and twist it out. Maybe there's a cover that comes off to make removing the lamps easier.
i'm not sure what kin of sockt their's uses but theres really no way get at the lamp to change it. my grandpa must know since he told me he changed it last in 2011.