Replace or

[further]

thoughts? Got the gasket surface good and flat. One of the inside walls is a bit thin though in a spot.

 

[Grub54891]

From my perspective, those don't look flat. Flat would be Shiney all the way around, milled or sanded on a flat surface. Filing don't work that well in my experience. Besides, you have a thin spot so it's just a matter of time before it damages the motor.

 

[Scott Danforth]

Use a flat surface and true up the surface

 

[jerryjerry05]

The exit is what you should worry about, stick a piece of wire in there and see if it's blocked and any rust comes out.
You can get the surface milled.