If your playfield glass lockdown bar (that's the metal piece that your hands
rest on while playing) is loose, it can usually be easily tightened. Open
the coin door and you will find a lever to the top or right side. Pull this
lever to the left. This releases the bar. You should then be able to lift
the bar straight up.
On most Gottlieb's you can just adjust the screws on the underside of the
bar. On Williams the adjustment screws are brass, mounted on top of the
strip of metal through which the bar fins pass. Clockwise tightens,
counter-clockwise loosens. On Bally's I believe you can tighten them from
underneath, but I've never found a loose Bally lockdown bar, so I'm not
On all machines, when you tighten the bar, you will find that the lever is
more difficult to move. Some small amount of lubrication on the sliding
parts will help this.