Onan 5500 issue

Starter problems with Onan 5500 genset. The starter doesn't engage, and it seems to be the solonoid. I have double checked battery connections. Even jumped it at the genset connections using a new battery. Still only get the low key chatter from the solonoid. My problem now, is that I can't tell where or how, to access it. My coach is a 2004 Coachmen Miarada. Can someone please steer me in the right direction?