thanks for the explanation
The way I read it is that you're just releasing the cable clamps, locking the gearlever and the gearbox shift mechanism in their reference positions then re-clamping the push-pull cables. ok so they can go back in a different positionThis in effect automatically adjusts their lengths so there is no preload or free play on either cable with the gearlever and shift mechinism in these reference positions.
It may be possible to check the setting without playing with the cable clamps. Just lock the shift mechanism then check if the gearlever locking pin can this just be a bolt or screwdriver presumably?...can be inserted without force.
If it can't, the cables are out of adjustment
Hopefully my ramblings will make the procedure a bit clearer