ArchaicArcane

Both Gutermann's Cotton and the Coats and clark are usually at least a 50wt. What does the C&C thread say for weight? The one I have here is a 50wt but lots are 40wt. The lower the number, the thicker the thread.

As a general starting place - 50wt = 80/12 or a 90/14 needle, 40wt may do OK with a 90/14, but you may need a 100/16. Definitely don't go down a needle size when you go up a size in thread.

You're better off with a 90/14, and I would suggest Schmetz or Organ needles. They're usually a known good needle. Dritz, I can't say I know anyone who uses them. Singer needles are also not what they once were.

Going down a needle size will cause the same effect of tighter tension in some ways.

With the bobbin tension a little looser, as per the way that Jamie suggests it, you may want your upper tension set a little lower than usual. Instead of about a 4-5, maybe a 3 - 4.

I can't name a single LQS around here that carries featherweight bobbins. Typically for local, you'll need to go to a Singer shop. Otherwise, if you're in the states (Which I think you are, by the Joann reference), I'd say Sew-Classic is your best bet.

If that's the case, you should have pretty reasonable tension between 3 and 5. Try it at about 3.5 ish because of where we put the tension on the bobbin case.

In your original post - post 7 in this thread? With the tension jacked to 9 as it was, I would expect your bobbin thread to show on the top. When we talk of loops on the top, it's actual loops. What you're seeing at 9 in that photo is only a little tighter than "the top of the bald headed man" as Jamie Wallen will say. (Was that in the video, or did I learn that in class with him?) That's an indication that your top tension is likely too tight or bobbin tension is too loose - at 9, your top tension is significantly too tight, as we'd expect. It's rare to get true loops on top. What gives the "top tension too tight away" is the fact that the top thread is laying on top of the fabric.

So, and I mean no offense with the following, since you say you're not a seamstress, I'd like to know the exact settings you have on your bobbin case and upper tension.

How many turns from tight is the bobbin case tension screw?
What is the number on the upper tension after you've done the reassemble and the fast tension test?

Here's what I think should give you pretty good stitches, since your machine is basically set up to my specs now

Needle: 90/14
Thread: 50wt Cotton
Upper Tension: 3
Bobbin Tension: about 1/2 - 3/4 turn from full tight

That should give you a result similar to this:
Top side:
[ATTACH=CONFIG]468967[/ATTACH]
Bottom Side:
[ATTACH=CONFIG]468968[/ATTACH]

You'll notice that on the top stitch line of stitching shows "the bald headed man" (tan thread is bottom thread) - that was the setting at 3.5 for my machine.

The second row of stitching is a little below 3 for me. This machine was set up before I figured out the "2" setting rule that I talk about in the video, so it might be a little off from what yours is, but it shouldn't be by much.

Notice though that if we turn it over, the stitching has switched, the bald headed man shows up on the bottom row of stitches. That means that "perfect" tension with these 2 threads would have been somewhere between 3.5 and 2.75ish. This is also somewhat affected by the fact that my bobbin thread is Aurifil and therefore very light compared to the weight of the C&C in the top, so properly matched threads might require slightly higher top tension.