I don't see any plastic, the straps are sewn, and the shoulder strap has two steel/metal spring-locks which attach to two metal hooks. (the kind Climbers use to climb mountains). However, thanks for the advice, I do not plan to use the shoulder strap anyway, because
I don't want to break my shoulder.
The PSR-9000 weighs too much to be carried on anyone's shoulder, unless the carrier happens to be Superman.
After checking it for carrying, I find that
the most secure way to handle it, is to have
two people carry it, one on either side of
the bag, one in front, one in back.

I do like the fact that those handles are
padded, conforming to the hand and giving
extra holding power. (leverage).
Thanks BEBOP.