Its never been taller then the post and I use an o-ring to line the hole up. Not touching the bottom. Tried with 0,1,2,3, nuts. Wick sort of tight in the hole. Loose in the hole. Took it back out and burnt more juice in. I oxidized one coil so much that it peeled like a banana. Folded edges of wick. I can get a nice even glowing coil that's killing the juice, But cap goes on and its over. I am about make a YT video.
@Striker.... reading your posts is painful man, so I can guess how it must be for you. As suggested by kickserve, if putting on your cap changes the game then perhaps follow the symptoms to the cure eh?
Get yourself a clear tank and try again. A gut feeling tells me your wick
IS touching the your tank (bottom or sides ) and/or getting jammed between the cap and the base, or, somehow moving within your setup to give you the pain the .... experience you're getting.
I have three DIDs, all with different coil/wick setups for different PG/VG mixes and they all vape perfectly, flavour and vapour (both UK spellings

and
DID require a certain amount of '
fiddling'.
Okay, on a very, very PERSONAL note, I've read a lot of posts regarding solutions to isolate the wick from the body, unoxidised wicks and the like and I'm at a loss as to why the giants of the industry (Jim being tallest in this instance, Scott being a close second and of course, the original French designer who gifted us this method) have not suggested these methods as refinements to improve an pretty perfect design. Ease of setup is an argument, valid for beginners I guess, but persevering with the '
fiddle' method WILL get you the desired result, trust me.
Your wick is the weakest link in the chain. Even the very best of glowing coils can't deal with a poorly oxidsed wick. The combination of a liquid with electrickery

-) requires a fine balance to achieve the results we seek. Perseverance is the order of the day, although a high frustration level is understandable when all around you are singing loud in the choir.
Just a very PERSONAL ramble.....
Peace