I also got a replacement pair of Sundara yolks for my damaged HE560 yolks. My first experience they wanted me to pay as I thought there might have been a possibility a slight drop it had could've been the problem. Amazon was good to me and allowed me to return it no problems. I had even explained that it was possible it was my problem, but still honored it. I just happened to take advantage of the sale on these as I did quite like them, and I bought a headphone case to keep them in at all times. I was not happy when I discovered the problem again, and I know this pair never had any possible error on my part as they were boxed away when I took them off.
I will say the repair process I went through was a bit different than what I had to do as seen in the video above. I didn't have anything like what is shown in the middle like is seen at the 10 second mark. I had the washers, 4 screws, and something close to the pieces seen to the left in the 10 second mark, but with holes to accept screws to be threaded into it. I figured I could figure it out if they didn't think to give any instructions.
I took the drivers out of the ear cup, and with careful balancing of a small screwdriver from an IFixIt kit for the first earcup I was able to use the screw facing outside the earcups with a washer over it, and then a washer between the headband yolks and earcups, and then what I would call the nut to screw it down. I found as I was doing it once the screws were initially in place and you placed the drivers back in there was no problem securing the headphones from the outside and could just finger tighten it using the nut. One of the drivers I did have a time getting back in on one side as the screw was poked out just a tiny bit, but oddly enough when looking at the drivers there was just the slightest of a notch in its circular body almost as if it was designed originally to be done that way. This process looks much better than I went through, so I'm not sure about that. Regardless, Hifiman did send a new headband, and I was able to get it working with the parts that I had sent to me.
I would strongly caution anyone buying the HE-560 to know about the reports of the yolks breaking. To me its not a matter of if they break to me, but when they'll break. Thankfully both pairs I have had happened within a month of time, and I was taken care of this time with a new headband. Not to mention two pairs broke in similar ways. The only way I could see they were breaking is from the pressure on stretching the ear cups out slightly when putting them on and taking them off when holding onto the ear cups. When you replace them with the Sundara headband my concern goes away. If they had the new headband at 349 my recommendation would be absolutely, but as it is now, I would still recommend with the warning this might happen, and be ready to contact HiFiMan in case, but know they did resolve the issue.