Plating a pin that was previously plated

I need to gold plate a pin that was previously plated. The plating
has worn through the gold and pink to a white metal in one small
area that prohibits the gold plating to adhere. Any advice on what
to use on the white portion when using an electro plating rectifier
with beaker system?

Robert

The plating has worn through the gold and pink to a white metal... 

That “pink” is probably copper. Plate the white metal with copper
first, then gold.

(Purists would suggest removing all the plating and starting over;
That when you re-plate over this, you’ll still have a spot showing
that is slightly lower than the surface. But it’s under the clasp so
don’t sweat it.)

Paf Dvorak