I totally understand & I could not have grasped it either (in my mind) until I put a dist in front of me, cuz logic says: if the mech adv moves the reluctor and the reluctor and the rotor are locked together (& they definitely are) then how could the mech adv shifting the reluctor so the light fires earlier (advanced) NOT shift the rotor tip at the same time to where it'd be moved further around the cap terminals when the light fires. it is a magic trick! put a dist in a vise or even in your hand and hold it so the magnet and a tooth are at say 12 o'clock dead even & note the shaft rotor notch position which is 9 o'clock on this one in my hand (rotor tip at 3 0'clock but immaterial to this). Keep the magnet (housing) at 12 0'clock & rotate the tooth CCW several degrees CCW (to the left). then hold the housing and lower shaft immobile & grab the upper shaft/reluctor & twist it CW to the right against the springs till the tooth is back lined up with the magnet & lo and behold the rotor tip (RP) is the same (9 o'clock/no change) with the mech adv maxed out. its a hell of a trick. Mr P body are you with us. After all this I could use a steak today!