In article ,
"Don Phillipson" writes:
The fluorescent lamp on a Kenmore Model 250 stove (now
20 years old) has started wrecking new fluor. tubes
(Sylvania, 22-inch, 18 watts). Symptoms a
1. Dark grey bars appear at both ends of the new tube
within 5 min. use.
2. Tube lights only at the two ends (dark in the middle
for 18 inches.) One end shows white light, the other pink light.

What does this mean?

Does it have a glow starter (when it did work, did it flash a
few times at switch-on before staying on continuously)?

If so, the glow-starter contacts have welded closed and it
needs replacing. The failed starter has probably wrecked the
tube too if it's been left switched on like this for a long
time. Simply unplugging the starter whilst the tube ends are
glowing should cause the tube to light up properly if a welded
starter is the cause and the tube isn't dead (might have to try
it a few times).

The darkened tube ends sound like the tube's filament coatings
have been substantially lost, and the end which doesn't glow
white may have lost too much for the tube to work anymore - that
would normally result in an orange glow though, not pink.

A second possibility is that the tube has an electronic ballast.
If that's failed such that it's providing a DC supply to the tube,
it will eventually end up with the mercury moving to one end,
which will continue to glow white, whilst the rest of the tube
glows a dim pink due to the remaining argon gas discharging.

--
Andrew Gabriel
[email address is not usable -- followup in the newsgroup]