That gooey looking hole just to the right of the tension assembly is a set screw, believe it or not. You definitely do not want to bugger this one up. I squirted some LW in there and let it sit for a long time before I even attempted to loosen it. I even took extra care to determine EXACTLY which bit fit perfectly in that screw. Ever so carefully I loosened it. I did take it out to clean but I put it right back before I lost it. Whew. Imagine trying to find that tiny thing on the floor of my shop.
Next, I loosened the thumb nut and removed it. I took this photo to show the individual parts of the tension assembly
This activity may be verboten, but I was very gentle and I did not force anything. The tension assembly was pretty stuck and just a bit of extra torque helped me loosen it enough to remove it. This does not screw in. The tension assembly is merely placed in this opening and the set screw holds it in place.
It is no wonder that this assembly was so stuck. I did apply LW to help. No damage was done to the threaded part despite my threatening it with a screw driver. Note the tension release pin protruding from the left of the assembly. It belongs inside, but I wanted you to see it. Don't lose this. You will be very sad if you do.
All cleaned up and back together again. Check out that needle bar. OOOO LA LA