@mymonkeyshines
Did you pull that "shaft to lock" button from the top of the dome on the router? If you put that button back, with the spring below it, and depress the button, does it then lock the shaft? Can you show a picture of the top of the dome? Can't tell if one of your pictures is of the top of the shaft, if not can you show us one?
The button and spring were actually in the carrying case with the router bits when I picked this up. The 2nd picture shows the top of the shaft. It is recessed into that brass threaded piece by a little bit so the button would be completely unable to touch it without an additional part. There is also a slot along the top of that brass piece, most easily seen in pic 3. I'm not sure what purpose that might serve. I can take a picture of the top of the dome later tonight. There is a spot for the button right at the top of the dome.
Looks like to me that the top of the shaft should have a flat section that should go into the slot section of the shaft lock button. It is hard to see if there is a flat section on the end of the shaft. It could have been damaged if the shaft lock button was pressed while the router was running.
If it is not damaged, to engage it you would have to turn the shaft while pushing down on the shaft lock button to get the two parts lined up correctly.
If the flat section is damaged then it is probably not worth the trouble to fix it.
Right now the shaft is a football shaped piece, seen in pic 2. as mentioned about, without some sort of additional piece there is no way the button could engage the shaft. the top of the shaft does look a bit beaten up although it didn't strike me as totally broken, but it is possible. there is enough a gap on the 'flat' sides of the shaft that you definitely could stick something in there to lock it if it was the right shape, I would think.
Also perhaps not clear from the pic is the slot on the button is not of one depth, but rounded as if to grab a circular piece, and deepest and the middle.