Filler tube help: a518

Hey guys,
I have a lokar flexible filler tube for my 518 that i bought second hand and i don't know if i was had buy the seller. My question is: how far down past the filler housing is the dipstick supposed to protrude? The one i have barely (1/8", maybe) peeks out below. It is basically useless and is a point of contension on my build. your help is appreciated.

One other question: will a 727 dipstick work correctly on a 518?

Thanks for your help.
Grant