How many months did you run your s9 before the fan damaged?
If it's still under warranty you can try to contact the support and send your miner s9 back to bitmain repair.
If you receive a miner just now with the defective fan then you can request for warranty replacement or product replacement
Check this
https://support.bitmain.com/hc/en-us/articles/115000024827-How-to-apply-specific-replacement-within-warrantyOr if your miner s9 had expired warranty or void warranty I think bitmain is selling fan replacement so you should contact the Bitmain support directly.
You can use this link to contact bitmain support
https://support.bitmain.com/hc/en-us/requests/new