In a message dated 98-07-21 23:48:40 EDT, Jonathan writes:

<< I hope you're able to resolve it. Would you be so kind as to post the
 final resolution of your jiggle when you find it? Thanks. >>

Several people have mentioned the possibility of electromagnetic interference.
No source of such interference (such as a fan) is apparent nearby. Could
interference somehow come in through the apartment wiring?

Jonathan's case seems to indicate an impending failure inside the monitor
itself. If such a failure occurs, or if I learn any new insights into the
problem, I will post the information here. Thanks to everyone who responded to
my question.

Bryan S. Tyson
Greenville SC