Scratches and grooves on plates can be fixed by grinding paste on glass etc.
I've seen mislignment issues in the holes in the pump end plates cause locking up, occurs when the bolts are done up.
It happened on my A10 pump which is actually an alloy A65 body with A10 drive end bolted onto it. Yes that setup works fine
. There are wider gears in A65 pumps so more flow
(just like the SRM pump).
Running a drill through the end plates to slightly widen the holes fixed the alignment problem. Just do the bolts up a bit at a time and whilst making sure the pump still spins over.
This might work, might not. I've also seen bodies tht have distorted and the gears rub, I'm not sure if THAT can be fixed by a DIYer.