This is the gist of what Budd Premack (86 Syncro) said on the subject
sometime back:

"You can also reach that recessed screw by using a flat blade screwdriver
bit. (the one that fits into an electrical drill.) The bit can easily be
turned by fitting a small open end wrench onto the hex shaft of the bit. If
you don't have the correct size wrench, you can always use a small
adjustable wrench, or even a pliers if you are the sledge hammer type of
mechanic.
It is easier than it sounds, but be careful to not lose the inner spring if
you loosen the screw and it pops out on you."

-----Original Message-----
From: Vanagon Mailing List [mailto:vanagon@gerry.vanagon.com] On Behalf Of
Brian T.
Sent: Tuesday, July 06, 2004 9:00 AM
To: vanagon@GERRY.VANAGON.COM
Subject: sliding window latches

Anyone know how to tighten the sliding window latches?
Mine are a bit loose and I don't see an obvious means