I reached out to oculus support to buy some replacement tumbstick pots. The answer is:

"... we don't sell or we don't have replacement for joystick part only. I would suggest you to send us your defective controller for us to review and check for it for a possible replacement."

That's pretty unfortunate. I suppose, we won't see these joysticks on sale until it becomes clear they are a much needed consumable. Hoping for the best though, in spite of all this right-to-repair buzz getting traction.

I also asked them, what is the part number - the support person could not find it out.