Here is a video (with sound): https://streamable.com/w8tgqk (You have to go about 0:20 in to hear the sound). I got unlucky during recording and the sound was more intermittent, but normally it's loud and almost constantly there.
This is the Blower/Supply Fan (Part No. 9317) from a Reversomatic HRV system (in a high-rise condominium in Toronto). It's either the RHRV-S100A or the RHRV-S100P, I don't think it matters because they have the same operating manual and parts list.
What are my options? From the sound, does it look like I have to replace the part or does this sound like something that can be fixed? Is this a particularly complicated fix or can I do it myself?