For the sander, I wonder whether you might hear a high pitched metallic squeal if a bearing is frozen?
Who knows? If it were my tool from the beginning, this would have never happened.
I bought the sander as part of a constellation of tools that included a panel saw, a job box, a vise, a couple of shop vacs, a table saw without a fence, etc. In other words, there was a lot of stuff to evaluate all at once within the hour or so of time that I had to review and reject or retain what was available and make a package deal offer. So I merely turned the sander on and off to verify that it ran.
Had I known then what I have since learned after dismantling the machine for component inspection before use, (something I had already planned to do, but couldn't practically do at the site of sale), I would have known immediately what to look for, as this shaft / bearing / hinge / belt arrangement is clearly the weak point in this particular style of disc belt sander. Searching out this problem has uncovered two similar failures in machines that are currently being eBayed for their parts content. Only the critical part that actually gets ruined (the shaft) is missing from the parted out machines, in both cases.
I boxed up all the sander parts and hauled it away to storage, to get it out from underfoot. If I haven't solved the shaft issue by this time next year, there will be yet another one of these cast iron sanders on the market for the parts content, without the critical shaft needed for the otherwise perfectly functional assemblage to work.
All the suggestions you guys have provided (plasma weld build up at a machine shop, turning down to size, or buying a shaft from Sears for a similar machine and changing out the woodruff keys to the D style instead of the radius end style, as long as the other relevant diameters match, or finding some cold rolled stock and having an entire new shaft machined) are certainly viable. Perhaps an even cheaper solution is to simply find another used machine. Or a direct drive import. Time will reveal the most opportune and expedient solution. The mission of this thread was to confirm whether or not I have a problem. I do.