Roger I've recently changed to refilling the AVS off the GGTS (use finger to plug hole at bottom). This way I can crank down all the fittings and when correct putting it on GGTS there is absolutely no flooding.
I used to do that but after a couple of mishaps (eww sticky!) now use one of the silicone caps that come attached to either end of KR808/D-1 carto's to plug the hole, i have 2 types one has a small nipple in the end and the other is a plain cap, when cut down to just under half length they fit nice and tight over the atty connection end and either type works but the one with the small nipple plugs the hole perfectly. So i fill like this, hold the GGTS horizontally, unscrew the telescopic section a little, unscrew the AVS and attach silicone cap, unscrew AVS mouth piece cap then main cap, fill tank then reverse the above stages and vape on.
(silicone end caps from 510 carto's also work btw)
EDIT:- Just thought i would add that my AVS is the type without the brass atty connector (does that make a difference to its function?) and has worked flawlessly from day one. The only problem i have had with it was after taking it apart for cleaning and putting it back on with the atty connection loose and of course it leaked into the collection tank! but user error aside it has worked perfectly.
