I use one of those adapters, looks like a heap of shit. Beauty/vanity rings don't come in the appropriate size to hide that gap, either. Tried grinding one down, but the one I bought was made of adamantium...
Try looking at the contact points of the adapter -- That center pin should be about flush on the 501 side w/ the threads. I just used a screwdriver to wiggle mine to a good position when it didn't seem to be working.
Bought a used 8 and Persei, light years ahead of an ego pen experience. Of course, for a LayG cart, discretion is the key point. With that in mind, why does no one make a good high-volume skillet like the gentleman's v2 MEGA? I spend more time loading than vaping the damn thing...
Anyway, the KISS was light years ahead of the Dr Dabber (VB dabbler clone, basically), so it should at least be able to compare to the new 3-in-1