Assuming battery but thought I'd ask the experts

[dbritt]

The battery cable seemed faintly loose and was rusted quite a bit. Brushed it with a brass brush and got good clean metal on the cable, nut and washer and tightiened it all down and then took that whole assemble and retightened to the battery post and vrooom off we go.

Good job! Many would just assume the battery was bad and buy a new one. In the replacement process, they would clean the cable terminals and everything would work great afterward. They would be happy campers never knowing they just blew $100 or more for nothing. BUT, if that battery is 4 years old, you may be about to experience Murphy's 3rd law: If something is going to fail, it will fail at the absolute most inconvenient time.