Not sure what you mean, but I think he has 10-speed (2x5, that is).

Suntour power ratchets were made in downtube, thumb, stem, and bar-end versions. The stem version is actually the cheapest and easiest to come by.

But this does raise a possible solution, if you find the "bad" thimb shifter is missing parts inside, or if something is broken: you could buy a stem-shifter version on ebay (probably $10-15) for parts to fix your bad thumby. Internally, they're basically the same.