KR-5 stuck aperture when on body

Hello, I just bought a RICOH KR-5 camera with a 55mm lens. When the lens is on the body the aperture only goes to 5.6 but when it is off the body it goes to 16. Would anyone know how to fix this possibly? I only spent 12$ on this but I'd really prefer to fix it rather than just take a loss.

You could ask at pentaxforums (they have an area you can post without signing up) as there's several Ricoh devotes there!