Remove all paint. You have to start from clean zamak (no paint left inside the lettering grooves).
Spray paint bezels satin black (not too much paint so as not to fill the lettering grooves).
Get hold of a small can of good exterior paint, preferably ivory colour than pure white.
With a small brush, fill the lettering grooves with ivory paint.
It is probably better to leave to dry one hour or so, but not a problem if not.
Use your best index finger and wipe off (most of) the excess ivory paint.
Wipe your index clean on a rag impregnated with white spirit.
Wipe off the remaining excess ivory paint a second time.
Normally, this is enough and the bezel should be perfect.
You can do it a third time, but at some point you will remove too much ivory paint.
In that case, you will have to do it all over again.
The key is to start with very neat lettering grooves.
Good luck !
A useful tip, while you have the dashboard out : at the back of the dashboard there is a recess in the wood which goes around the instruments. Paint this recess in two coats of pure white. The dashboard illumination will be much brighter when everything is back in place, especially if you fit LED bulbs. “Night and day”, litterally !