Not sure if you got this solved already or not; but for anyone else who is stumped by it as I was
(I took apart one end of the button to nearly loose all the springs DO NOT REMOVE THE SCREW UNDER THE SWITCH ON BOTTOM!
and then nearly breaking it trying to get the base off).
"PUSH" the white plastic clip on the side of the button assembly "IN" (the white plastic clip shown on the TOP side, in the picture above)
While holding the white clip "IN", pull gently apart the top button and base switch sections.
Cut 7/8ths of an inch hole where button is desired.
Remove plastic NUT from thread of button side; then insert button section into the hole.
Retighten the nut snug.
Re-attach switch side of assembly ("PUSH" white clip "IN")
Release plastic clip when assembled.
I ordered and am replacing a few buttons on my machine. I found this video
that breaks down a similar emergency stop button to the one I purchased from LO but the key difference seems to be that the LO button has a lip that prevents me from sliding the button through hole in the chassis. Because of this lip I don't really see how I'm supposed to get this button flush with the chassis. I've attached a picture that shows where I think the button is supposed to sit. Any help would be appreciated.