I've had several people remark it seems risky to remove decals, etc., from diecast cars and from locos - and does it even work - just alcohol?. I don't want to encourage anyone to try something they think might damage something precious, but removing decals/painted labels with iso alchohol really does work and it seldom goes bad (but yes, once in a long while . . .).
The photo below shows what I did by doing nothing more than taking time and keepsing a delicate touch. This is a 1:43 a Cisitalia 1000 coupe that was very important to me. Not expensive ($11 plus $13 shipping from Germany) but it took ten years to find this one. Why so important. This is a 1946/47 car! A red one is in the Metropolitan Museum of Modern Art's permanent collection: the first long-hood, full fender, fastback sports car with "the look." BTW - this was a tiny car, a tad smaller than a Porsche 356.
Anyway, it is extremely irksome that diecast manufacturers put racing numbers on just about any model that is sporty and Italian. These were not decals, they looked to be printed/painted on. Regardless I removed these and others in the past with nothing but a little iso-alcohol and time. This is where what your father taught you is very true - take your time and work slowly. Using a Q-tip I first dabbed liquid on to the numbers and kept them wet for about ten minutes. While I have used Q-tips for the removal in the past, here I used a wooden matchstick covered with a tiny bit of soft cloth (tee shirt) wetted down and rubbed, as much as I could, on just the number itself. I did see traces of silver - just traces - on the cloth so I was concerned, but . . .
The key is to take time and work at wearing down the painted label in this case - this took 45 minutes of just gentle rubbing with the matchstick and wet cloth. I think of it as very slow wet sanding. It seems forever that nothing happens, and then gradually the numbers appear to be getting lighter in color, then foggy, and then they gradually fade away. Note, just barely visible in the lower left image in the picture: I was able to leave a tiny printed/painted "Cisitalia" on the front cowl while completely removing the racing numbers from the hood. It was only about 1/16th inch from the numbers I did remove.
