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David

WD40 contains, I believe, silicones, which are insulators. It's good sprayed on the outside of, say, igniton leads.

Silicones on a sliding electrical contact are however bad news - adding extra insulation exactly where better conductivity is needed.

Respectfully suggest you use, on the sliding contact of any rheostat, 'Contact Cleaner' fluid sometime called 'Switch Cleaner'. Obtainable retail in the UK from Halfords.

Good sailing and vanning 

Michael Bradley

I'm afraid WD40 was all I had handy at the time and certainly the only thing I had with a big long spout. I must admit I always use WD40 near electrics with a certain amount of trepidation, because in theory it shouldn't work, but it usually does.  In this case neither lamp was working.  After cleaning both bulb barrels with Autosol chrome cleaner and using WD40 the scale light worked brilliantly.  The bubble light was slower and weaker to come on line, but improved with use.  Fortunately, it doesn't need to be very bright.  I'm afraid I was also tempted to try a little petroleum jelly on each end of the batteries, so there can be little hope for me. DaveP