Recently Zepher ?? Herb submitted a tutorial on tightening up a floppy mirror head for the twin post mirror. I had a very nice one, that had that problem. Herbs well described information was very valuable to me this past week. I did do some alterations to his directions. Where it said to install screws and tighten down till the desired tension was obtained---I used longer machine screws, flat washers, lock washers, and TWO nuts on each screw. In that order. I ran the screws clear to the bottom of the newly threaded holes. Then I cut the machine screws off, short enough not to hit the inside of the mirror glass. In essence, making studs out of the screws. That way the tension is adjustable and the second nut locks the two together. Later on, need more tension? It is now adjustable. BTW Menards and probably other building supply stores ( Lowes- Home Depot etc. ) has the drill bit and correct thread tap in one package.. about $5.00.
One other thing for Herbs directions ..be careful in drilling off the peened heads that holds the flat spring plate. To do a good job, it has to be drilled right in the center of the studs. ...............................MO