I used this link. It will let you select up to 4 joy-cons to mail at a time. I don't think it even asked for a reason on this form, but it does ask you to send some basic info w/the controllers-name, address, phone, and a brief description (I just wrote "significant amount of drift" ). They emailed the UPS label almost right away, but I couldn't print it out; there's also a link to a barcode that the UPS store can scan and print out. All I had to do was box them up and go to the UPS store. Shipping both ways was free.The Fife said:
How'd you get in contact with them, through whatever warranty link there is on their site?
Fix Yo Joy-Cons