So many variables beyond what we control.. don't think from that perspective that if you do everythign the same it'll be the same. even with clones...
9 of 10 problems is an abundance of something or everything cuasing an issue. I don't know what that is, sorry.
watering -- wait for top 1" to dry before watering. Give a thorough watering until ~10-20% runoff helps reduce buildup and toxicities from occuring.
If you haven't done that, do that for a bit and see how it reacts before doing anything else.. unless someone tells you with certainty what it is, of course..
i think you have multiple things going on (again hints are overabundance) and possibly pH related too.. if you haven't controlled that, get that in check too before doing anythng drastic... work slowly up to solutions that can be a double-edge sword if not right -- liek adding anything.
Check out my link in main profile comments under Maximizing yields... go to miniute 44 or so.. explains what i mean and why 9 of 10 issues are self-inflicted due to overfeeding.
Also, read watch all of them... some of the best information i've found. Based on research and not bro-science in someone's closet with a sample size too small to draw any rational conclusions about.