I thiink the slide plate on that door is in the door side.  That said,
sag such as you describe is usually caused by a worn pin in the hinge.
I replaced mine with a hardened roll pin from a local hardware store.
Real bugger to drive out as the access is a bit tight but if you
remove the pin in the stop bar you can get it open enough to get at
them.

If it just bangs on the latch pin at the rear (where the door latch
grabs) then that pin is adjustable as well - but the alignment problem
is again normally the worn hinge pin.