If it usually works when you press on it, it sounds like the strap might be too loose so I'd try pinning (to test) and then perhaps cutting/joining the strap as suggested. Does it work reliably just lying down with the pickup pressed firmly against your chest at bra line? Given that it's paired and has a new battery, I can only suggest any firmware updates that haven't been done, or contacting Garmin Support. I use the premium strap which adjusts easily and no problems, but I had no problems with the previous monitor either.