AR xa Turntable Head shell question

Long as it holds firm, great. Only thing I don't like, duct tape adhesive tends to get all goopy over time. If you want to try something else, teflon pipe thread tape or a strip of aluminum foil. 

Each of these should of course have a different affect on the sound. Even budget gear like this you will probably be able to hear a difference. I'm assuming these are all very small pieces we're talking about, ie not enough to have to worry about VTF.

No self-respecting sufferer from audiophilia nervosa could put up with duct tape as a solution to that problem.  Did you try jamming the head shell with some force, up against the receptor on the arm wand?  The trick is to let the collar catch on to the pin at the top of the male connector built into the headshell.  More than once, that has been a problem, until you apply enough force.  It may not be "broken", in other words.  Once the pin is engaged by the collar, twisting the collar will retract the headshell up against the contacts, and you don' need no stinkin' duct tape. (Actually, I am surprised you can make good solid electrical contact with duct tape holding the thing together.)

A new head shell?

https://www.ebay.com/itm/Best-Audio-XA-Headshell-for-Acoustic-Research-AR-XA-and-XB-Turntables/33229...