I just purchased a new plane that came equipped with a Stratomaster E1. Of the 3 flights I've had in the plane, the RPM only displayed properly once and I can't figure out what the issue is. Admittedly, I haven't really had the chance to trouble shoot it yet but I'm hoping if I describe the symptoms, someone else who may have experienced the same thing can get me pointed in the right direction. It is monitoring a Rotax 503 with points ignition. The scale is set from 0-7000 RPM. I don't remember what the RPM calibration is set to but I will be checking that first along with all connections and grounds. The gauge fluctuates very quickly between 9999 and 5000 RPM at full throttle and between 9500 and 4200 at what I think is close to 5500 - 5800 RPM (based on sound and aircraft performance. Any ideas what might be going on here? Thanks guys!