I had a problem with some fluorescent light fittings recently. It took me a while to track down, and even after a bit of Googling haven't found mention of it before, so I thought I'd pass it on.
I have some 4ft T8 tubes - nothing fancy, cheap battens from Screwfix I think, a few years old - in the garage. One of these stopped working recently. I thought it was the starter, so I put a new one it. There was a momentary strike as I turned the starter bayonet, but then nothing.
So I thought I'd buy a fancy new LED tube instead of a replacement fluorescent. Put this in (with the shorting starter ... and nothing.
Hmm - strange for the ballast to go, I thought ... a quick measure seemed to indicate that at least the ballast seems to have volts through it.
I was starting to suspect the entire fitting - I'm not sure how reliable the end connector to the pins are on the tube - when I finally worked it out.
The thin 'copper' plates on the socket for the starter were deforming out of alignment. So when I turned the starter, the pin wasn't making a proper connection as it was supposed to.
A little tweak with a VDE screwdriver, I made sure the contact was made as the starter was turned, and ... bingo! we have light.
So, an easy fix, but one a problem I'd heard of before. I shan't tell how long it took before I got around to diagnosing this...
Cheers Jon N