We installed a new evolution this year.Sometimes though it won't light after you push the on button.If i push it off and back on again then it lights ok.It doesn't do it all the time though.I just cleaned it yesterday so i know it's not dirty.It lit fine last night and again this morning.I had shut it down when i left this morning and came back a couple hours later and tryed to start it but it just droped pellets and wouldn't light again until i pushed the on button on and off again.