You would be correct if you made the distinction between a genuine K4 and a [ah-hem!?] copy.
I have two genuine and six "copies". Two of the copies have never been opened. One of those, made more recently, is a dead ringer for the original, down to the tell tale clue for copies not being present. It goes in the atty museum along with some other FT stuff.
Two serve as bases for bell caps (so I can distinguish them from the real thing). They
vape "okay", better than the myriad sub-
tanks. One I dropped into the garbage last night 'cause it won't work no matter what spring goes in it. The sixth I use, off and on, with the PMMA
tank. It, too, will soon go to the dump since it needs constant adjustment of the 510.
So much of the K4 complaints come from confusing the real from the counterfeit. Genuine: no problems. Counterfeit: headaches.