Well it appears the above issue wasn't the only problem with the damned thing. It suddenly stopped working again so I opened it up and had another look. Having checked the movement of the control switch I found two sprung power contacts one of which looked as if it wasn't making good contact so I bent it slightly, reassembled the thing and sure enough it all worked. Or so I thought... After a few on/off cycles it stopped working again! On reopening the casing I couldn't see anything obvious but shining a high power cree led torch on the contacts and their soldered connections I could see one of them had failed. I've never really done any soldering but have a kit from many years ago so dug it out and had a fiddle. After a few mistakes I managed to form a nice neat bead of solder on the dodgy joint and then tested the contact to make sure it was secure. After reassembling the switch casing it was bingo!!! Yes, it's all working perfectly again and after all these years I can chalk up my first success with a soldering iron.
