I've had the HRM that came with my Garmin Edge 800 for roughly a year.

At some point in the last few weeks, I realized that it was not properly working. Heart rate was significantly different (by something like a factor of 1/2 or more), but I don't know how to best diagnose if it is the strap or the actual electronics/transmitter?

I am assuming the strap since it appears to be transmitting to my Garmin fine, just not correctly measuring the heart rate. However, before purchasing a new one I thought it would be prudent to check here.

Thanks