My new employer has LOTS of the 110 4 mix trimmers and edgers.. Today, I was trying to diagnose one that ran like this: VERY difficult to start, when running it would either not rev up like it should, or it would rev instantly to red line at times. It would just not run consistently.. I thouroughly cleaned the carb, checked for plugged exhaust, and even checked the valve lash, which seemed real loose for this little engine ( probably somewhere around .020" or so). Any Ideas? I wondering if maybe a bad crank seal?, or a problem with the reed valve? I was unable to lash the valves, as I don't know the spec, and I was unable to check compression, due to the weird little plug (although it did seem good just cranking it over.. I'm game to Ideas/ suggestions as this is the first 4 Mix I've ever laid hands on, and probly won't be the last.. I also tinkered with another that acted like it was missfiring at high Rpm's ( banging out).. Are these things prone to coil failures? Almost forgot, the first one is two seasons old, the second is a year old.. Also, bossman said that MAYBE non-mix gas was used ( not certain )?