[Kurt in NJ]

A disc that is not the same thickness in different places can move the levers uneven too, to adjust you need spacers that are exactly the same thickness to take the place of the disc

perhaps there are shims between the release lever yoke and the cover---or it needs some(under the 3 bolts)between the yoke and the cover----but you need a method of clamping the springs to take the pressure off the yokes