I have a 2170 which is essentially the same machine (i think). I love it and would not want to replace it!! I usually never have a problem with it.
I never wind my bobbins through the needle. I too never use the thread cutter. When piecing using this machine, I always use leaders and enders (small pieces of folded fabric). I find that much easier than holding the threads. I also use the 1/4 inch foot as well as the stitch plate with a single hole in it.
Weezy Rider had some good advice. One other question - have you changed thread type? have you changed bobbin thread?
When I have problems, it is usually lint under the stitch plate. If that does not fix it for me. I start from the top (new needle, re-thread completely, check tension). I then do the bobbin. Check to see if your bobbin is loaded correctly. When the bobbin is in the case and still in your hand. if you pick up the thread end the tension from the flat spring should be enough for the bobbin case to lift off your hand then slowly fall back into your hand (mine is actually tight enough I need to jiggle it a bit for it to fall). After inserting the bobbin case, I always pull up my bobbin thread to above the stitch plate and have a 2-3 inch piece pulled to the back.
If you are still having problems - try a leader - for me it works perfectly. Sorry to hear you are having troubles. I have two of these machines a 2170 and a 2054 and love them.
Good luck - let us know haw you make out.