Update
In the interests of full disclosure, this experience did not turn out to be quite as perfect as originally described. The rubber diopter ring, which had been removed and reglued, came fully loose again (more of an annoyance than anything) and I noticed that when racking through a lot of focus travel (ie, from a feeder 20' away to a distant hillside), I was actually getting some diopter drift, which I had never experienced with these before. My ZRS were sent back and forth a couple more times, but the problem wasn't resolved. After I received them back the last time from ZR (and after I had spend more than $50 for the initial "repair" and two more postage fees), Charles answered exactly one of the many emails I sent him, saying he'd get back to me, but despite numerous attempts to contact him after that (including leaving phone messages), I never heard from him again. Finally, following a few weeks of frustration, I sat down with the binoculars and racked the focus and diopter all the way in and out for an hour or more, while I read news on the internet. I also cleaned out the sloppy re-glue of the diopter ring. After that the diopter adjustment seems more reliable in terms of keeping its setting. Now they can become car binoculars or loaners. It became clear, though, that Zen Ray's seemingly generous warranty isn't actually as easy to employ as the warranty from companies like Leupold, Bushnell or Vortex/EO.