Scary crap, over fire or defective part?

Had a pretty significant overfire a few weeks ago. Checked out the stove, no cracks or warps, didn't think anything more about it. Lately noticed decreased draft. Checked my key damper and felt "stuff" in there when trying to turn it. Figured it was the perlite/thermix insulation, so took the stove out, reached up into the liner, and felt a gaping hole above my block off plate. Removed the block off and found that the liner connector had failed at the straps, which I assume were spot welded to the connector. Pretty scary stuff. Is it possible that the heat could have melted the welds off, or is it more likely that the welds were defective? I don't like that I had to remove my block off plate to see the damage. If the insulation hadn't fallen into the chimney I don't know when/if I would have noticed it. Going to contact the liner manufacturer and get a new connector. I'm thinking of putting some sheet metal screws through the straps. It's impossible to put my plate above that joint. Thoughts/suggestions?

I'll need a riveter. Going to call the liner vendor tomorrow to see if they honor the warranty. If they don't, you'll all know who it is I'm disturbed because this never crossed my mind as a possible failure point. Stove was fine on my initial inspection. Going to go over it closer now that it's out.

Wow, that was fast! Called the liner supplier (royal chimney). Tech agreed that the part sounded defective, and that those spot welds shouldn't fail. Sent me the new connector, got it today. Also said that although the welds could fail, he hasn't seen it. So I don't know if the rivets are necessary on the new part. Tomorrow I reinstall and give the stove a good once over. Great customer service from royal chimney.

Well, we're back up and burning. Close inspection of the stove, no damage. Only problem was the block off plate. Originally installed before I put durock/heat shields inside the fireplace. Proved impossible to put the shield back in correctly without taking everything out of the fireplace, which I wasn't in the mood to do. Not sure how much good it's doing anyway, since the chimney is insulated top to bottom with thermix. I may take it off altogether so that I have full visual access to all the joints in the chimney system.