I can't see the gap in your picture. The pump looks nice, you did a good job on it.
If the hinges were bent- about the only way to fix them is to heat them up and straighten them. Use a good straight hinge as a guide.
The side panels are held onto the frame with bolts that have a very flat head. If you used a standard round head stove bolt the heads may be causing the gap. Use a truss head bolt (screw).
There was no rubber or bumpers that I recall.

ROD [Mich.]