After reading the EG&G manual I now understand the special light filters that are missing for my unit. Since the light output for the three flash speeds is so different, they had the equivelant of Neutral Density filters to make the 10-2 and 10-3 speeds the same intensity as the 10-4 speed.

Rather than relying on gelatin or acetate filters that may fade with time, or rather than the expense of pure carbon filters they used a very simple solution.

The filters are just sheets of plexiglass that are black or painted black and they have a series of lines on them to controll the light intensity.

One filter has 3 slits and the other has 19 slits.

Last night I cut 2 pieces of plexiglass to the appropriate size and then painted one side of each with semigloss black paint.

Today I will mark out where I want the slits to be and just scrape the paint away using the blade of a fine screwdriver. I can then fine tune them by adding or removing more paint as directed by flashmeter measurements.