On Mon, 22 May 2006 04:55:24 -0400, Nelson
wrote:

Sears Blower DC Motor Speed Control, PCB #7004317-00

Component has two leads, upright rectangular epoxy case about 1 cm
square, 5 mm wide with ".047J400" stamped on top. I'm guessing it's a
Diac, but I can't find it listed anywhere.

D1 is likely to be a diac.
Your little rectangular box contains a 47 nF 400 Volt capacitor.

--
Kind regards,
Gerard Bok