Paul, et al

Replacing the Negative Solenoid will sometimes only be a temporary fix. When the issue is either the actual wire from the Input Negative Post on the side of the Onan to the Negative Solenoid, of the connections of that wire, replacing the solenoid with a new one will temporarily solve the problem. But when the contact points in that solenoid become slightly used, the total resistance of the Negative circuit to the starter increases and you experience slow-starting or non-starting, again. It is time to permanently solve this issue.

I am convinced that the Onan internal wiring (Positive & Negative) from the Start Battery Input Connection Posts is insufficient and should be replaced with larger wire. See below and see attached pages from my Amel Book.