I also feel a certain 'non-linearity' to my 935 quill spring pressure down around 70% of travel. Its not a problem, but also not the silky smooth feel like when I first traversed the 935 table & said mmm... me-like-a. The down force tension feels about right, maybe a bit on the resistance side for small drills. But I figure if I reduce spring tension it will retract even more sluggish than it does now. OTOH I also don't have much run time yet so maybe things loosen up a bit over time? I'm strongly biased to only one machine, my ex RF-45. It was smooth & linear tension going down the whole travel & self retracted quite quickly. Not unlike my drill press I guess.