When I tried to start my YM2310 on Saturday I noticed sparks from the engine compartment.  So, I opened the hood and observed while I had my son try to start the tractor.  I saw sparks coming from 1 of the two large lugs on the end of the starter solenoid.  I tried to start it again and just get a loud clicking sound when I turn the key all the way over.  What do the sparks mean?  Has anyone experienced this?  Thanks.