Ok so my point is if you are trying to use a different spur you have to be careful it is no thicker than the original, even slightly otherwise the button head screws protrude further out which pushes the pully further out and then you end up tightening the washer and screw against the bearing which causes the binding.
As for the guy having problems using a panaracer spur I have no idea, have you isolated it to the lay shaft? Or have you checked to see it is not something else causing the bind as other common binding issues are putting front spool pulley on back to front and not centering the rear diff correctly.