The Lamp Room

In our garage we have a pair of mid 90's Fitzgerald 6's.
They seem to have developed a disliking of the cold and can fail to start in sub-zero. Initially it was just one that had a T12 Sylvania (the other had a 2010 T8 Philips), the Sylvania was swapped for a T8 Crompton and the problem went away. After a while I put a pair of 827 Hombase T12s in and they'd take over 40secs of blinking to strike and pluse starter didn't want to know.
The Homebases were swapped out 12 months ago for a pair of Thorn EMI Pluswhites. They worked well but when this winter came in they started to take a while too strike too.
I put Arlen pulse starters in and they were fine but when the temp goes below 0 they occasionally fail to strike (sometimes one, sometimes the other, sometimes both).
Thoughts, pulse starters on their way out?

If there are capacitors in series with the ballast, those might be failing

There are capacitors in a pulsestarter but they are related to the preheat timing rather than the striking. If they fail it be visible by the starter preheating too short time or not working at all

They only have power factor caps in the fittings as they are jut switch start/preheat.

On rare occasions the capacitors on 6’ are in series a shunt capacitor like on 8’ 125W

Them Homebase tubes can be a bugger to start. Otherwise the only thing I can think of is that you have low voltage at the fixture

All the other lights in the garage seem fine. I'll have a further look at them. I have swapped the pulse starters out for a pair of LEL UM2s.
I need it to go ver cold again though

Try tube covers to keep them warm.
I've had this problem with 8's in a cold building. They're turned on in the morning, electronic starters don't start but as soon as the heating is on and warmed up they're fine.
Failing that, check for a low supply voltage.

As Kev says, check the voltage at the fitting. Low line voltage sounds the most likely cause.

Could they be having moisture problems? Isn’t that why some have silicone coatings?

I thought this matters only for starterless gear ?