which levers are you using? can you post a pic? are they early C-Rec that have a finny little plate you need for aero? if so and the plate is missing the feel/function will be awful
also you said the calipers are almost brand new. are the pads 20 something years old brand new too? are they correct size and not overly worn? try some new brake blocks before swapping out the calipers.
PS when you toss the calipers in the trash bin let me know so I can fish them out.
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“One morning you wake up, the girl is gone, the bikes are gone, all that's left behind is a pair of old tires and a tube of tubular glue, all squeezed out"
Sugar "Kane" Kowalczyk