Cruise control driving me nuts

[Stempy]

I seem to have a never ending series of faults with the cruise control. Firstly the vacuum pipe split, fixed it, then the brake pedal switch went duff, fitted a new pedal, then the relay burnt out, fitted a new one, then again today was cruising along and blluuurghh, cruise control gives up. Not had chance to investigate other than a quick relay swap to no avail, but any ideas welcome