I could use some advice on fixing my WASR

[djturnz]

I think I figured out what is wrong with my WASR-10, but I need some advise on how to fix it.
Some of my magazines go in and work fine, but I have a very hard time getting them out. The release is very stiff and I sometimes have to use the back of another mag to get it to release. This only happens once I've fired a couple shots from a mag. Usually I can just put a mag in and then pull it righ back out with little trouble.
I also have some mags that the bolt actually hits the rear of the feed lips and it will sometimes not go into battery.
Well I think I found the issue. The area at the rear of the magwell, where the mag release is riveted on, looks to be slightly curved up (towards the inside of the receiver). I figured that this is causing the magazines to seat too high.
I guess I need to bang that back down so that it is flat. What do you guys recommend as a good method to do this?
I copied a picture from gunsnet to illustrate the area I am talking about.

[einheit 13]

Grind the top of the mag latch down first. You'll have a hard time bending the receiver without deforming it.