Hi. My name is*****'m a camera repair technician with over 20 years in the business and I'll be glad to help you with your question today.
I can not find a Canon part with the number you provided. I believe the part you are looking for is the focus encoder brush, part # ***** Is that correct?
The unfortunate fact is, Canon no longer supplies parts for this lens and this particular part is not available from any source. I've broken a couple these brushes myself and have had to repair them by soldering new fingers onto them. Suprisingly enough, this works and can save a nice lens from the scrap heap.