Thanks everyone who replied.
The 475 connector body (ie: the part that incorporates the outer, probe sense, ring is secured firmly to the front panel with a nut. The nut is not loose and won't move under power of needle nose pliers (it would require some sort of really thin wall socket, I think). Between that outer ring and the next "ring" (ie: the BNC shield proper) is a layer of nylon(?) insulation. It is that layer that is loose, allowing the entire BNC portion of the connector to float within the body. I can look all the way around using a mirror, and don't see any sign of a set screw. Unless it is under the nut, I don't see where one could be.
If anyone knows the part number or a source for the style 3-conductor BNC assembly used on the 475 front panel, I'd love to replace it. In the meantime, as a temporary fix, I stood the chassis gently on it's nose so the connector was vertical with access to the back, and drizzled in a few drops of thin cyanoacrylate. I wiggled and jiggled the connector to work the cyano in as deep as I could before letting it sit and set up. That firmed things up mechanically -- for now, anyway.
That leaves the resistor.
So much debate about a 10? part. Probably every single one of you knows more than I about the subject. I suspect a couple of you have forgotten more than I know about the subject. So when one of you says that a carbon composite is a better choice for this application, I think it's worth listening.
That said, after careful consideration, I decided to stick with the original Tek-speced carbon film resistor. I don't use this for any high-energy measurements. I mostly use it for things like transistor curve tracing (my digital scope is great but sucks at XY display) combined with a personal bias towards restoring old equipment as opposed to modifying old equipment. But thankyou again for the input.
