Cavalier 55 - only dimes work

Hi - I just get a cavalier 55. Its very clean and the coin mechanism is a National rejectors model (mechanical).  should it take something other than dimes? The coin mechanism looks really clean, it has a 'correct change' light that has a good bulb but doesnt light up, and wiring for the light. However, only dimes work, nickles and quarters drop thru. It seems like it should or was designed to based on the wiring etc. It puzzles me because I would have expected the 'correct change' light above the coin entry slot to stay lit.
Any ideas? thanks