Mark Levinson - how to fix white logo paint that has peeled away?

Are the letters grooved into the front of the unit?

I think that I would try getting some paint that I could thin out enough so that it runs a bit, then set the amp so that the face is horizontal with the ground and dab it in with a something a bit smaller then the groove (pin/needle).

There are paint sticks such as this that are designed specifically for filling in engraved lettering or lines.