I've eaten 3 of the HF tumblers. I've learned a few things:

1) Buy the extended warranty, it is dirt cheap....and chances are you will use it at least once.
2) Always tighten the top, extremely tight. I've recommend adding a few large washers. It will help secure the top. I even add another bolt, wing-nut to ensure it does not come off.....
3) Don't overfill with cleaning material or parts.

I have never had the end bolt strip. The most common problem I have had, was the wing-nut working it's self loose. When this happens the lid flops around; and usually bores out a bigger hole in the lid (destroying it). Ejecting material all over the place.....

If the threads are stripped, assuming it was possibly cross threaded....

Since this, I bought a high-end tumbler...The high-end tumbler is slower, and has less issues. But, ironically the HF until cleans the parts faster...... I now run both.

Ratcheting?

Yikes, I haven't needed to go to that extreme. And the threaded shaft on mine is ok. I'm guessing if you/he used a wingnut that didn't actually match the threads on the shaft.

The cover is a bit deformed on mine now, though--I may have to get a new one soon.

Ditto the extended warranty - I seldom get them but it pays off on the HF tumblers. Give it some heavy use when new, the ones that fail mechanically usually die just over a month or two of good use. My first one failed at seven weeks - motor got extremely hot, couldn't touch the bolt for a bit, melted around the cover hole - pulled the warranty receipt and have used the replacement ever since.

Turn that wingnut until your thumb hurts! I failed once and like Force the hole became a larger oval. I added a metal washer on top of the rubber one under the lid, added washers on top of the to raise above the damaged thread, been good for two years. I have learned to verify that the wingnut does not move after 20-30 minutes then it can run for days if need be.

Blew out two of the smaller units myself. I gave up on them but the larger one has served me well.

After wearing out the hole twice in lids, I decided to fix the problem by reinforcing the lid. Added a metal disk under the bottom, riveted and fiber glassed in place, and some metal riveted to the topside. Works great now!

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Have you thought about using a wingnut made out of a softer material than the bolt? Like brass, or vinyl? It should bear most of the wear and be easily replaced.

If the threaded shaft became stripped, simply take a thread chaser to it (also available at HF, ironically) and clean/renew the threads. If its so stripped that they won't chase, which is unlikely, re-thread the shaft down to the next size. IIRC, the current shaft is 1/4-20.

I hand tighten the wingnut and then insert a nylon insert lock nut on top of the wingnut. The lock nut ensures that the wingnut doesn't move.

Norm I believe it is a metric M6 Rod. Easy to change out to a 1/4" x 20 Rod. It will continue to strip though. The fix is what bznhvx did. Marvelous.