Stupid question but... woudn't this cam rotate even without balls? On my Grand Prix 2010, the middle cam does not really touch the mast (no rollers, no balls) but rather "floats" around it. Maybe you could try loosening the mid batten or adding spacers to the other cams. For safety you may also put protective tape around the mast.
The old Gaastra cams didn't have rollers or balls, nor the NS soft cams, nor many others... and worked well.
Last edited by Farlo; 20th February 2013 at 11:18 AM.