Copied from a reply I made to a similar thread on BritBike.Com:
(I replied to a fellow who found a horrendous amount of grunt inside a new Amal Premier carb, I gave my take on the issue, then someone replied that I might be referring to NOS (old Amal factory) carbs)
My reply:
I was not insinuating that they were NOS (old Amal factory), just that they may have been new "Premier" stock, but from an early / earlier batch that were out the door BEFORE they implemented the "after-construction cleaning" step on the packaging line.
This could easily happen with a reseller involved - Reseller buys a large lot of early production Premiers, shelves them and starts selling them, some of which have debris in them. In the interim, Burlen modifies the shipping routine to include a cleaning station before packing. At the same time, the reseller still has some new (early production) Premier stock with debris in them. Recent buyer purchases said carbs with debris (unbeknown to reseller), and it looks bad to Burlen, even though they have since take steps to eliminate that issue.
(that's my "read" of it, anyway)