Knits are tricky, but if your aren't sewing anything different than usual, the tension should be ok. I don't have this machine but if it is set on a 3 or 4 it should be good.

I asked about the bobbin because I had a similar issue a while back and the problem was the bobbin. I had bought a pack of bobbins that I thought were the same size that came with my machine, but of course, they were not. They were a hair smaller and a tiny bit shorter. Those bobbins made my life hell for about a week until I finally realized that was the only thing different. I threw them all away. No more clucking. Another time, I had dropped the bobbin in with the thread going to the left instead of to the right. I was still able to do a few stitches then the whole thing would go crazy. I swore up and down it was in the correct way, but after much frustration and stepping away and coming back a couple hours later, I removed the bobbin, and stared at the little diagram and flipped it over and voila, no more craziness.

I really do hope it is something simple.