The front weight of keys are calculated, heavy in bass, light in treble. For the weights marked with letters, each letter represents a pattern. Small leads are 6.8 grams each, big leads are 14.1 grams each. I.e. weight "C" represents two 6.8g leads, weight "D" represents two 14.1g leads, "F" represents three 14.1g leads.
Pick and move weight on key till the pre-calculated Front Weight (F) is achieved.
Use the pattern to mark key lead locations.
Drill with forstner bits, 1/2" bit for 14.1g leads, 3/8" bit for 6.8g leads. Put leads in drilled holes and double check front weight.
Press leads into keys firmly.
After leads are installed, paint sharps with black paint for a uniform look. Let dry over night, then put keys back to key frame for the next steps of adjustments/ regulation.