The new growth looks super healthy, that's partly why I'm so confused about what might be going on. There is a bit of browning going on with the new growing tips, but not nearly to the same extent as on some of the older growth. If the tree had mites or aphids or some other pest, it seems that the whole tree would be affected equally. Same if there were some kind of fungal issue.
When you say dampness issue, are you suggesting that I'm overwatering and not giving the tree enough time to dry out?
Maybe, maybe not. I was just curious because I have a tendency to overwater in our climate, especially in the winter, and particularly after I've worked a tree. I forget that less foliage = less water needs, but don't reduce my schedule. I had a juniper that I worked hard, over watered and kept in part shade before I really knew much about them. It looked pretty crappy for a year and a half before I wised up, repotted it in catcus mix and left it alone for two years. This year finally it's pushing lots of non-stressed growth. Fertilizing regularly helped too.
From the other thread, it looks like your juniper got a significant foliage reduction last year, yes? Perhaps it's still sulking a little. If there's more new growth than die-back, and the dieback is just little bits here and there, I'd probably wait it out through the summer and see if it gets better on it's own. But if you observe it's getting worse, or want to be cautious, you could treat it with an antifungal and/or a systemic pesticide. I do this from time to time as a Spring preventative or if a juniper is starting to look a little stressed. Just make sure you shelter it from super hot sun for a couple days after treatment, as some treatments can cause additional stress damage if the foliage gets sunbaked after application.
But I'm pretty new at this, so take my advice with a gain of salt.