Kaweco Sport disappointment

I so wanted to, and still want to love my Kaweco Sport fountain pen, but it is hard to do. It is still my go to for making notes, but is also a bit infuriating. I hate to give up on it. Wondering if I just have a lemon? It was great for a few weeks and then the cartridge consistently became dislodged - thanks to this forum I was able to fix that w/ a spring from a ball point pen. But the the the flow of ink is scratchy or non existent. Any thoughts to how I can rectify this?