Why do I have to jiggle power cord will not stay green

The color changing simply means it's charging your battery. The outer ring of the AC plug jack can get spread aprt thus preventing secure connection. It can be squeezed back till it's tight. You may also have a damaged DC-IN port. That can be replaced but only after you are sure the jack is tight.

Here's the part you may need: [prodotto collegato mancante o disabilitato: IF155-065]

Go here to exactly identify your correct PowerBook before ordering any parts: http://www.ifixit.com/Mac-Parts