This happened suddenly, put a load in and started it up and it sounds like a Model T. It doesn't shake or vibrate excessively. My son cleaned the lint trap before starting and the top of the dryer gets a lot of junk stacked on it so it is not impossible that something fell in to the lint trap recess but that's just for informational purposes. Any thoughts? Here is a link to a video with the sound:

https://drive.google.com...ZV7Osou/view?usp=sharing

Thanks.

SOLVED. Opening the top and starting it briefly, the noise seemed to be coming from the lint trap housing. I but a fiber optic inspection camera down there and saw that there were tiny nicks in the same place in each of the blower wheel's blades. That convinced me that something was hitting them, probably something that fell down the lint trap housing.

Opened up the back, took the housing off, and a large gray plastic jar lid (among other things) fell out. I didn't see it with the fiber optic camera probably because it is gray and nearly as wide as the housing opening. Cleaned out the lint, put it back together, and all's right with the world. My wife is so happy she is "taking me out" to dinner. (I still pay but she doesn't have to cook).