Play at the pivot where the main lever mates with the shaft it rotates on, shutter blade pivot pins, and delay gear pins all add up in conjunction with weak springs to cause poor speeds. With the tension removed from any rotating part check its side play, shutter blades and delay gears should turn freely with no side play; operating levers should have less than .001 inch side play. Check pins, shafts, and mating holes for roundness, machine and sleeve elliptical ones.