Apple Watch ECG app problems

My ECG app doesn’t seem to work properly. Its Model A2477 version 10.3.1. When I touch the crown it either doesn’t read, it tells me to hold my hands still, or it repeatedly gives an erratic reading. Usually I have to hold my pinky on the crown in an odd position to get it to work if I can even get a reading at all. I’ve cleaned the back, around the crown and performed a hard reset. It got marginally better after the hard reset. Here’s the thing. My previous watch read ECGs perfectly and was crucial in finding and diagnosing an issue I was having with SVTs. If I’d had this watch at that time I never would have caught the SVT. (I’ve since had 3 ablations and that issue has been corrected). I don’t know what else to try.