I've had my trusty Sten for years and had no issues (apart from replacing the original sub standard battery that failed with one in a case).

However, today it cut out a few times and the only way to get it back on appeared to be wait briefly, disconnect battery, reconnect..
Looking at it at home, it would appear that tapping the cable close to the lamp body causes it to cut out. So I'm guessing cable issue of some description? Has anyone else had similar issues and is it easy to rectify or get spares? I've got no idea on electronics, so simple would be good

Roy Fellows may be able to help you:

http://www.ledcaplamps.com

I think he has the remaining UK stock of Stenlight spares.