I recently purchased a used 2010 Enviro M55 and had it installed. There is power to the unit, however when you push the on-off button it won't start. I have cleaned it, but haven't been able to have it professional serviced yet. Any suggestions on what to troubleshoot first? I don't think it has been used for at least 2.5 - 3 years. The guy I bought it from said it worked the last time he used it.