you could try this site here
http://www.keeptheheaton.com/acatalog/Potterton_Fans.html
the fan you should need is a FAN ASSEMBLY - SMITHS FFB1706 the manufacturers part number is 409568 and the gas council number is 381853 (only needed os you go through british gas)
what you need to be aware is these boilers are on limited stock of parts so dont expect parts to be available forever!
hope this helps
ps im in no way connected with the site i provided i just searched the info that i know and found that site!
KAW!, September 2007
