I bought a electric ignition converted 31cc ryobi engine off rcu and ran into a problem, I will do my best to explain it,
I have narrowed it down to the Sensor and was wondering if any sensor would work as long as the magnet was aligned with the sensor? what the bad sensor is doing is it will spark with i turn off the attached on/off switch to discharge. I can get it to send a charge from the battery but it does not return the spark when the prop is spinning..any suggestions? will any sensor work? Thanks for your help!

Depends on what ignition it is equipped with. The condition you describe is what a failed hall sensor will do when the switch is turned on. Sensors are rather easy to come by but you need to determine what system it is associated with. The most common is the type used with CH and RC Exl ignitions, but there are others as well. Some are not hall type but instead use a puck up coil.

The CH type is quite inexpensive so might contemplate giving the,m a call and describing what you have.

Try flipping the sensor over, or the magnet, polarity matters.