Options: I could mail back the M2 to KEH for return. It would take up to several weeks for technicians to evaluate—if they agreed with the assessment, postage both ways would be refunded, along with the purchase price of the camera. No offer on their part to evaluate for need of a CLA at this point, but I am sure I could mail it back for them to evaluate. KEH holds up their end of the deal, but because the buyer is the one to actually use the camera, one can be looking at easily a month or two to come to an agreement about what work needs to be done if any to get things right.
The M2 I received looks quite nice but has been heavily used, to point of needing a new sprocket and other bits. During previous rebuilds it has received new bottom and top plate, and many new screws, which is why it looks so good, or EX, on the outside. It seems like a new sprocket and gears will get it into fine shape.