I've been using Fusions in my Liquinator for quite a while now and haven't had any issues with the draw - I've even gone from double-slotting to single and it works well. I use it on an 801 connector, no adapter.
However, I know of one person who had a draw issue with her Fusion recently and it ended up being the carto itself - even after she tried a few classic tight-draw carto fixes and she ended up having to just toss it.
Can you remove the Fusion from the tank and check the draw without too much mess and see if it might be the carto instead of the tank? If not, maybe try a second one and see if there is an improvement?
Good luck to you - hopefully someone else will chime in with a few more ideas.
