If the tension is balanced the stitch will look very much the same on the top and the bottom. On light weight fabric you will see an equal size dot of thread on the top and the bottom, just as you described. When you spread the seam open, and pull it apart, are the stitches nice and tight, and do the top and bottom threads meet equally in the center?

I have noticed the slight slant you are mentioning. I have noticed it on machines with a rotary bobbin system vs the oscillating bobbin system. However, I am not sure if my observation holds true, maybe someone else here knows.

Regarding the unnoticeable tension change when pulling the thread and changing the tension setting. The tension disks are open (not applying tension) when the presser foot is raised. Try it with the presser foot down.

Debs.... Thank you for responding! You told me just what I needed to know. My machine is performing fine, I was just paranoid! I didn't realize the tension wasn't applied when the presser foot was up so that's good info!

You are welcome. Here is a tip we often forget about. Please forgive me if you already know this. Make sure the take-up lever is in the highest position before removing or putting in your work. This ensures that the needle thread isn't still wrapped around the bobbin case and that the stitch is completed. If you have ever had difficulty removing your work, for example, it was hard to pull out and more than one thread was coming up through the hole in the needle plate, it means the take-up lever was not up.

Have fun with your machine. I am glad I am not the only who "plays" with them. So glad you said that. Thanks, Deb

vacuumfreak - I just wanted to also add that the picture you posted helps alot of us determine how to help. So many machines are different and we can only talk about what we are familiar with or that maybe look similar. A picture always helps. Have fun playing. Budster