[Mr Gazza]

Flip makes a good call with the general relay. It's a good to spare to have around anyway, as he says, but personally I wouldn't store it in the bike as it's subject to possible damp, heat and vibration.
I had a grumbly general relay on my first Monster. I couldn't get to the dealer for a while, when it played up, but I helped it along for a couple of weeks by putting it in my pocket when I got to work, this ensured a reliable start up for the run home.
Try putting your relay in your airing cupboard or on a radiator for a day and see if it makes any difference.. Keep your spare relay somewhere dry and warm.

I did also experience the old broken wire in the loom round the headstock syndrome on that one, on another occasion.