I have a 2005 2 stroke Merc 50, tiller handle, electric start, power trim. Sometimes after it sets for a week or two, the starter does not work. I can hear an arcing noise when I turn the key, but the starter does not engage. I can usually turn it off and back on a couple of times, and it will start. Then it usually starts right up for the rest of the day. I can't find any loose connections or corroded connections. Any ideas? Thanks