[Zelandeth]

Thanks for the responses, guys.

Will get one of the bulbs out to see what they're rated at (though brightness wise they look about what I would expect), after that will take a look at the thermistor. Given the slow, smooth (amost intentional looking!) way they fade out over a period of five to ten seconds, I tend to think that it must be that at fault - a dodgy connection would be rather more erratic I would have thought.

I don't have the guide, but someone did send me scans of the relevant pages, so I've got the diagrams and such (though no doubt such books will become a necessary purchase at some point...I've already discovered that this is an addictive hobby).