UPDATE:
All had been well for a while longer. I did start planning to build my next keezer. But after returning from a week long vacation on 10/28, I poured a beer and was surprised that it was warm. My keezer had finally bit the dust.
I, of course, pulled out my trusty freon charging stuff again but found it wasn't low this time. So whatever was the demise, it didn't seem to be the freon unless there was some related problem that didn't manifest as low levels. What ever the case, it was running but not cooling at all now.
Sadly my new keezer build hadn't progressed more than buying the new chest freezer and some misc parts like CO2 distribution manifolds etc. So that's what I've been working on every weekend since then.
I'm looking forward to my new keezer but to anyone reading this, it takes longer than you'd think it should; especially when you have limited time to work on it.
I think I'll be lucky if I have it finished and put into "production" serving beer before Christmas. SWMBO isn't too thrilled with all the time I'm spending building this thing over the weekends. Not letting this project monopolize my weekend free time is only extending its finish date.
If you've found this thread because you have found yourself in the same low freon boat I was in, the takeaway is that you may be able to squeeze some more time by charging it. Heck, I got a little over 4 years more time. But don't get complacent thinking you'll just recharge freon till the cows come home. Because they will come home when you aren't expecting it and leave you with warm beer and a pressing project.
I think most, if not all, of the new chest freezers use cyclopentane instead of freon. I know my new one does and I've noticed that big cyclopentane sticker in several others keezer posts.
I have no idea if they can be recharged like this, I'm thinking not. Hopefully this new keezer lasts long enough that I wont need to find out. Time will tell...
EDIT: I may be confused about cyclopentane. Sounds like it may have more to do with the foam insulation than the referigerant. Hard to tell though; I find many references to it being a referigerant as well.