I bought a M- series for 40.00 that does not have spark. I installed a new cdi spare that I have and still no spark. Its more than likely that I have a bad sensor, I believe there are 3 of them. I need to know if they are normally closed or normally open to do a continuity test. Also this M series does not have the blade clutch. I think its either the oil level sensor or bag sensor(I believe it has bag senor). Engine has good compression and I noticed that the pistons are 2 ring. Thanks