An answer was posted in the HP business customer discussion group that seems
to give me just the help I needed (I haven't tried this solution yet -- I
have the part on order):

by David B.

August 12, 2003 21:36 PM GMT
Bob,

You need spare part # 302005-001; this is a retro kit for the screws that
hold the heat sink to the processor. Eliminates the need for solders. Fixed
my problem and if you already know how to get into the machine, you've got
3/4 of the problem solved.

Several other people here have had the same problem, and this is the most
cost effective solution. The part was $15 when I bought it; others have said
they've jacked the price to $45. Still worth the money if you're out of
warranty. Beats the cost of replacing the board, and if you get an OEM board
as a replacement, you'll have the same problem again in 6 months.