I have a Kawasaki air compressor item #691531. I have had good very good service from it since since 2009. However, the O-ring for the drain is now broken and it's always losing compression. I have been to all the hardware stores in my area and the smallest O-ring I can find is 11/32, which is too large. Where can I find the right size O-ring in my area? My ZIP Code is 94596. Thank you, Trevor Gray