Anne, if the tension disks are clean and the machine is threaded properly and you're still getting loops on the underside even with the tension set as high as it will go, there are two main things to check:
1. The tension on the bobbin thread may be too tight. When you draw on it, it should unwind smoothly and easily, but it does require some pull. If it feels tight, turn the bobbin tension screw a quarter or half-turn at a time and test the appearance of the seam.
2. The needle thread tensioner may need to be re-set. There are instructions in the little green manual for taking the tensioner apart and re-assembling it correctly.
The thread should draw through the needle almost effortlessly when the presser foot is up. After you lower the presser foot, the thread will be noticeably more difficult to draw through the needle. It should pull the needle to the side.
The 201 is a decent FMQ machine and it has a huge amount of room under the arm, which you'll love. Some people do all of their quilting on this model and prefer it to any other machine.