Lionel Legacy GP-7 Smoke is either on or off

Just a point of continuing education...there are no dashes in EMD diesel model numbers. You have a GP7, not a GP-7.

The only place where EMD used dashes in their model numbers was in their "Dash 2" series. The SD40-2 model is an example, as is the GP40-2, GP38-2, SD38-2, etc.

Thanks for the info Rich, now I know.

The exact Lionel product number of the GP7 would be useful in answering this question.

John, It is 6-28353. Erie Diesel GP7. Thanks.

Since that's an early Legacy, the top suspect is the smoke regulator module.  The smoke unit isn't doing anything to smoke volume.  However, since that unit has the 6 ohm resistor, when you replace the regulator module, replace the resistor with the 8 ohm one, that was recommended by Lionel years ago as the 6 ohm resistors were too hard on the regulator modules and caused premature failure. (sound familiar?)

Thanks John. That answers my question