maybe wet flowed means they are dunked in a vat of alcohol, then rinsed off ? no excuse for finding particles or shavings in a purchased part except for lazy workers. before i retired, i fought with the guys that worked for me that their job was to drill and tap a 1/8"NPT with a 1/16" through hole in an iron regulator body. super simple job, and it required a simple blast with air to clear the chips from the hole when completed. that blast of air was important, because if not done, the iron chips would compact in the hole after running through the washing equipment, rendering the small through hole useless. and after sitting on the shelf awaiting assembly a day later, those leftover iron chips turned into a huge deal to remove ! upon flow testing, the failed regulators were returned to my department to be disassembled and inspected to see why they failed. almost all that failed had iron chips packed into the previously mentioned drilled and tapped hole. caused again, by lazy assemblers that couldn't take a second and look into the hole to see if it was clear. all started by workers [unfortunately mine] that were lazy and did not do a simple procedure that was REQUIRED when the work was done initially. i even paid close attention by being present when the work was being done [and it was done perfectly then], but when i left, back to being lazy ! it is surprising i have any hair left.... this tale might not be carb related, but just illustrates similar machining irregularities happen in other products as well.