K1 sounding rough

[Dean Washington]

Anyone else's k1 sounding rough? Or just mine? at middle to high speed it starts, picked it up and when it gets to that point a horrible vibration goes through the car, I had a look and tried different things, and I've narrowed it down (i think)to the spur/slipper assembly, at that point I noticed if I held either side,(the nut on either side) it had 1mm play, is that normal? Also does anyone have ideas on what this could be?