After scanning many message boards about Sears/Craftsman garage door
openers, I found a lot of problems with their logic boards.

Yesterday I had a Sears technician troubleshoot a chattering originating
from the long screw in the channel (3/4hp screw drive model), and he
mentioned not to use 100w light bulbs due to excessive heat, especially on
the logic board side -- the one where the wires connect. Even though my GDO
is rated for 100w bulbs. He says the heat is the main cause of logic board
failure. He recommends only up to 60w.

For some reason, that makes a lot of sense. Indeed with the 100w bulb in
there, the plastic casing even with the metallic reflective foil became very
hot.

SO, reduce the heat by using lesser wattage bulbs. Hmm...wonder how compact
flourescents would work.

BTW, the chattering...he squirted WD-40 (?!?) and declared the sound as
normal. Sucky tech, but at least got some good advice from him.