Garthwood

mike early................both of my .72 have the black plastic back plate. Never had any problems. Maybe some folks are warping that plate when re installing the screws. The tightening sequence is crossed and not clock wise or anti clockwise. Not too much torque.
My other Saito 100 (2) and the 120 have the aluminum back plate. A friend of mine has the .82 same thing. Sound fantastic.