I have had to replace the flex brake lines on both a 944 and my 928. after rebuilding the calipers the old rubber hoses were restricting the release of pressure. on my 928 also found the master cyl was clogged and restricting release flow on the rear circuit.
I am pretty OCD about brakes.
here is what I found in the calipers off the 84 944. primordial sludge? fortunately they cleaned up nicely.
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Bob Cox
78 930 clone project car.
87 924S resurrect at some point.
84 928S, Ruby Red linen/brown interior - sold
86 944 turbo my new DE/track car - sold