Have been restoring my old man's La Scala Butterfly and I'm 99% there..... but I'm now having issues with the boiler water level probe. I picked up a new probe, but not the teflon sleeve. And I think I may have damaged the old one (which had seen better days anyway) when reinstalling it.
I've got a coffee repair guy next door to my office and he should have them.... but I forgot to bring it with me today.

I think they are a 1/4 fitting, but wanted to see if anyone here knows for sure? And is it worth replacing the boiler nut (and possible a copper seal?)?