I got a Colt A2 upper, that the port door won't stay closed. It appears the notch for the door latch is worn, and the pin holes are also enlarged. If I push up a bit on the door, it will stay closed. Anyone have ideas for repair, or repair parts? The other alternative is a 5lb hammer!

The dust cover? Leave it open.

Some folks might say an worn A2 upper isn't worth the effort or cost to repair.  But if you want to save that Colt upper, I'd get a hold of someone with a Tig or Mig welder and add a bit of extra material so the  ejection port detent would work properly.  The oversize pin hole is more difficult because you have to re-size the hole after welding.  Since the welded area is exposed, you might have to refinish the welded area and it's going to be hard to match the color of the upper.  You might want to try using just enough JB Weld to reduce the size of the inside diameter of the pin hole.  That way you don't have to worry about touching up the finish.  Hope this helps

$10 fix

Thanks, I will order one and give it a shot.

OP,  I was in the same boat as you. I have an older Colt AR15/SPI that I bought used. It was at a good price, but in a little rough condition... Broken/cracked handguards and the upper receiver had some serious dents/dings/scratches, with one straight down the ejection port, which caused the dust cover not to lock or even stay in place.  I wanted to keep the rifle 100% and after debating the cost of getting it fixed, I simply bought another used Colt AR-15/SPI upper receiver to swap it out with.

Now, I have to get both the upper and lower receiver refinished so they match.   With this said, swapping out the uppers is the easiest way to resolve this issue...  If you want to keep the retro/early look.

Good luck!!