Found a replacement at Ace Hardware store - they had two in stock: Ace Wire-In Touch Dimmer (item# 3007044) Specification: 120V, 60Hz; 150Watts maximum; Incandescent bulbs only; 3 light level. (It is actually a Westek Touchtronic 3-level dimmer control Model#6503). Cost at Ace is~$9.00.
See the following Ace web page:

http://www.acehardware.com/product/index.jsp?productId=1286174&cp=2568454.2632232.2632330.1259267&parentPage=family