No mate, don't suspect the dealer service. I reckon the previous owner may have used the wrong type of grease and it had become contaminated. Also, since I cleaned the connector, I did notice the odd flicker of the red light so I replaced the wire that connects the switch to the connector under the instrument panel. Since then it has never even flickerd. I'm a qualified electronics technician so it's been done professionally. The wire must have been chafing to the chassis somewhere so suspect this was the main cause. I've been to the dealer and he agrees that this is the most likely cause.