ok so I have a garmin 705 edge and it's been tempermental at best but this one really puzzles me.  I switched wheels and the cadence reading wouldn't work on new set.  checked everything but nothing.  switched back to old wheels and nothing again.  really frustrating.  so changed batteries, actually read manual about resets and.................nothing.

I train using the cadence and it's really bugging me.  anyone got any ideas before I ritually disembowel myself in my shed?   thanks