*sigh* there are several blog posts I would point you to, but I keep getting my hand smacked for pointing people to uh,.. a site that may or may not belong to me. I could have shown you timing things, tension things, 99 bobbin area things.
This will help some though:
http://www.quiltingboard.com/vintage...g-t195869.html
As will this:
http://www.tfsr.org/publications/tec...achine_manual/
First, the stuckages could have to do with an intermittent catching of the top thread. When it happens, gently pull on the thread to the left of the tension disks, does it move relatively freely? (it will have some tension on it, but shouldn't be "Stuck". ) If it doesn't, pull on the thread on the right side of the tensioner, is it free? If it's free on the right and not the left, the problem is either the tensioner or something (duh!) to the left of it.
If it's not, I would first check the spool to make sure you're not catching on the little "slit" on the spool.
If it's on the left: check the needle plate, the entire thread path for burrs. Can you post a photo of the stitches, preferably with a different color in top and bottom? (If you take the throat plate off and watch the stitch being formed, it's also very enlightening... that top thread does a lot more than the average sewist thinks it does.
Screw "EE" being loosened and things being adjusted are not the end of the world.