Fortunately, I have not had to deal with this issue. When you go looking for a welder to fix this, ask to see some examples of the aluminum he or she(you can only hope, lady welders do awesome work compared to their male counterparts. Yes, sexist but true) has done. Steel is a piece of cake, stainless is a challenge, but aluminum is a whole other ball of wax. Once you find a welder who does good work, they will know exactly how to fix this issue. I think it will be a matter of cutting out the old weld and then filling it back in with new material once it is in the proper position. I would also suggest you look just forward of the door and make sure that the section of channel is in the right plane with the door. In the photos it looks as though the bottom lip is pushed out just a little. This might be because it is not in as far as it should be. This might also be due to the bad weld(s). I think you might also have a little adjustment on the hinges, but am not certain on this. The 71 we are currently doing has a different door hinge, but allows for a lot of adjustment via bolts holding it onto the door. Your era is just a little younger than we normally deal with.
Sorry I missed your call. I left my phone charger at home and the battery died first thing in the morning. Try me today and hopefully I can help you out.