UPDATE: Well, ho-ho-ho.. On my way back from a job interview today I decided to stop off and have a well-earned cigarette. Cigarette smoked, I got back on the bike, thumbed the start button and nothing. It's been a bit temperamental over the last few days but a jiggle and more thumbing sorted it out in a few seconds. This time though, 20 minutes went by and nothing. Yes, I checked the neutral wire/switch, side-stand switch and jiggled more wires and did all I could do when you're at the side of the road with no tools. I got onto the shop I bought it from and asked if they'd recover it and they gave me a number of a company to call but before I dialled up, I tried the start button again and it started. Grrr! Anyway, long story short, I rode it to the shop, told them about the start problem which they knew about when I phoned them for recovery and said while they were at it, would they mind having a look at what's causing and possibly diagnosing the rattle. I mentioned the head bearings and what I'd done with megawatt's advice and they said they'd take a look at it today and certainly by tomorrow so hopefully I'll have a reliable, rattle-free bike by the weekend. Apparently, the start button problem isn't unique to me.