the old pads may be compressed from age.
Try getting some new ones, very cheap part, and compare them to the old ones. if they are thicker, that might help. I would also verify the springs are not lowering springs.
'92 300CE - Sold
2004 C240 - C7 Wheels
2015 ML350 - P1, Pano, Ash poplar wood, Sport Dinamica interior, Running Boards Keyless go.