[QUOTE 4954829, member: 9609"]the curious thing is the problem is the other way to normal, it is registering too many clicks. I have certainly had problems in the past with poor connections that result in lower milage as clicks are missed.
I still tend to think this could be a problem in the wire, for instance if the insulation has broken down then vibration could cause shorting hence 'extra clicks and extra distance' . But the wire seems fine and it is only lightly tapping the reed switch sensor that seems to recreate the problem. (but I'm sort of thinking may be a reed switch could register with vibration, but then again forks on a bike wheel suffer lots of vibration so may be they don't ?)
Anyhows, I do remember buying a new cycle computer a few years back before I managed to fix the one I am using. If I can find it I can user the sensor off that to help identify the problem.[/QUOTE]
The reed switch does vibrate and make connections from noise other than the magnet. The switch even bounces and makes two or three connections per magnet revolution but the computer cancels that out by recognising it as noise. Yours maybe has dementia and forgets to cancel the noise.