Sir,
I have had good luck with Castrol Super Clean (in the purple bottle) or Simple Green cleaner and a stiff bristled brush. I like to take a cheap bristle, sometimes called a chip brush, and trim the bristles back to where they are pretty stiff. A 3/4 inch to one inch wide brush gives good results. It takes time. I get my Super Clean at the local auto parts supplier.
Scalecoat paint remover is another choice. The Super Clean smells a lot like it - not a very scientific test - so it may have similar active ingredients.
Using these compounds I have removed Floquil and Scalecoat from brass, Floquil Polly-S, Scalecoat II, and water based craft paint from plastic, and factory paint from Atlas (in HO), Lionel Postwar, and MPC.
Please do not leave any of these solvents on the model overnight; some plastics will become brittle with prolonged exposure.
Another avenue you might explore is that the remaining ink is so thin that the grain may not be obscured. A thin overspray of an easily removable type paint such as a water based white might reveal that the detail is in fact not obscured; the overspray can then be more easily removed and the repaint can continue.
I would recommend using an undercoat to even out any color variations prior to applying the final colors.
V/R,
Mike