Mazda 6 Service Manual: No.19 excessive shift shock on torque converter clutch (tcc)

No.18 excessive shift shock is felt when upshifting and downshifting

No.20 noise occurs at idle when vehicle is stopped in all positions/ranges

Other materials:

Mazda 6 Service Manual: Manual Transaxle Shift Pattern
  The shift pattern of the transaxle is conventional, as shown. Depress the clutch pedal all the way down while shifting; then release it slowly. Your vehicle is equipped with a device to prevent shifting to R (reverse) by mistake. Push the shift lever downward and shift to R.   ...

Mazda 6 Service Manual: Air bag module and pre-tensioner seat belt disposal procedures
Warning Before scrapping a vehicle with a live (undeployed) air bag module and pre-tensioner seat belt, deploy the air bag module and pre-tensioner seat belt. Never dispose of a live (undeployed) air bag module and pre-tensioner seat belt. The air bag module and the pre-tensioner seat ...