I have an AMD-65 on which the dust cover will not stay on because (it appears) the rear trunnion is set back a little too far. How much should it cost to have a gunsmith fix this? I am not an AK builder but I am thinking it may be expensive since the rivet holes in the receiver would (it seems to me) have to be wielded and then redrilled? I know a (somewhat) local guy who could do this but I need to know what a reasonable cost should be before getting an estimate.