Garmin Forerunner 301 problems
Ya, mine did that - I ended up just swapping it out with Garmin. They have a quick turn around.
Are you out of warranty? They did my HRM for free but was under warranty.
Another time I broke my 301 - it fell off the bike at 25mph! They fixed that and I believe I paid less than than the $80 you quoted.
RV
It takes a long time to get good. - Scott Molina
Slow is smooth; smooth is fast. - Rich Strauss
Did you make sure the battery in the strap is in the right way? I'm good at putting them in wrong.
I had the HRM strap on my 301 die at one point. Long out of warranty, but Garmin after trying to help me get it working just sent me a new strap and I've had no troubles with it since. It helped that I had a couple 301s and I found that the one strap wouldn't work with either device, while the other strap still worked with both. They were very helpful so I'd give them a call or email them before just sending it in for repairs.
I had the opposite problem---the device stopped picking up the HRM. My boyfriend's would pick up my HRM; my device would not get either HRM. I called Garmin and they replaced it with a new/refurbished unit for free even though it was about a month past the official warranty end. In any case, even their $80 fee isn't too bad when you consider the cost of buying new, and it's a way to recycle.

Has anyone else had their heart rate monitor just up and quite on them? I changed the battery in mine and now it won't work at all. It won't pick up any readings what so ever. Its been 3 weeks and I have tried everything (including what Garmin says to do to troubleshoot the unit).
Before I give up and send it to the company for repair and an $80 fee I wanted to see if anyone had a fix.
Thanks