Hi, I am not an expert but I have been doing ALOT of embroidery for approx. 8 years now so see if any of this makes sense. For the thread it sounds like too much tension is being put on the thread from the spool, do you use a thread net? it helps the thread feed off the spool more evenly, change your needle again, even a new needle may have a "spur" catching the thread. As far as the outline goes, it may just be the the design itself, if it is more than one design doing it, what type of fabric are you emb. on? anything with a "nap" needs a topping to keep the fibers down flat, I use tulle instead of water soluable, it's cheaper and works really well hope this helps a little

Pick a part of the machine and watch what happens when the thread breaks. Then, do that for another part of the machine, and try to find where the trouble spot is.

Mamakat talked about thread coming off the spool unevenly. watch the thread. Is it coming off the spool is a near continuous straight line, or is it popping off with a lot of extra and making little twists before it feeds into the machine? Those twists and large curls spell thread death.

Watch your bobbin, too. I was, for a while, using a bobbin thread that was too weak for normal tension, and the sucker would snap, bunch up, get stuck in the needle and cause a jam. I also had an improperly wound bobbin that had alternately loose and tight winding and that, too, caused jams. There as a time when I forgot to put the bobbin thread through the lower tensioner and I couldn't figure out what the heck was going on, when I finally did I realized I gotten into the habit of not properly threading my bobbin.

Look for lint. If the thread is rubbing somewhere strange in the bobbin or in the feed then there will be left over bits of lint.