That makes sense, My last plastic, has worked since it's been in. I think some of us had a burr from machining the threads inside the base, and this initially damaged the threads. Mine base was sharp on the inside, after I ran the sandpaper in it, it removed the burr. Iatty base felt smooth inside afterwards. My friend it using it now, and has had zero problems with it, and it works as good as the day I put it in.
My suggestion, since I think Imeo is right on the money on this, is if this has happened to you, and it's done it repeatedly do the sandpaper trick I described in my previous post to make sure the burr gets removed

Then feel in there an make sure it doesn't feel sharp. Put in a new plastic, and you should be good to go!