| Gary, You are mistaken in assuming that early style sprockets are worn based upon the spline alignment in Ash's picture. The front part of the piston helix can be rotated to give this illusion. Please see the pictures below, both are of the exact same piston in which I easily twisted the front part to show the amount of available movement. Note in the top picture the helix teeth are inline on the outside but offset on the inside. Note also that the exact opposite is shown in the bottom picture. Also, this is not a sign that the six springs are shot, it is merely another built-in clearance of the apparatus that is necessary for the VTC to function without bind. 
Ash, this is for you: You asked me to comment about how my stronger internal spring may effect the "bite" of this split piston onto the camshaft helix and cause accelerated wear. I will have to refer you to my plot below of the torque that I measured from the camshaft to activate the VTC to full advance. *IF* a stronger spring were to increase the "bite" and therefore friction, it would show here as a progressively increasing amount of torque relative to spring force. But what you see here is a linear relationship indicating that friction has not increased and accelerated wear will not occur because of this. Now, I'm not about to tell anyone the scale of this plot, but what I will say is that I tested in excess of twice the current spring load that is being used in my rebuilds now and this data can easily be duplicated by anyone with a bunch of properly sized springs and an reliable torque measuring instrument. 
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