Thanks for the suggestions.  I think the problem is mostly the denim fabric but I will try all of these suggestions next week when I can get back to it.  When I first brought my machine home I stitched out most of the designs and was amazed at the great results with these stitches.  But that was with cotton and stabilizer.  I even tried it again on that same piece of fabric and can't get the same results.  At the time I knew very little about my machine and used nothing special in the way of thread.  I think I'll also check to see if I can adjust the tension successfully on other stitches.  Maybe it's somehow stuck in the middle.  I think I may even try some of the old invisible thread that I have.  I guess it's possible that I used that originally but it looks like I just used white bobbin thread.  Unfortunately I should have stitched out the stitches with black on top and white in the bobbin but I used all white.  Someday I'll try them all again..  Thanks again.
Ceil

Mulling this over more, I do recall trying both Bottom Line and Monopoly before trying Microquilter. Bottom Line was a little thicker than I wanted to show, and the Monopoly pulled the bobbin thread up some but not completely. Since Monopoly is a single strand of fiber rather plied filaments, it's not as flexible. It also may be susceptible to stretching.
Jan

I like to use my walking foot and a large 16-17 needle. And the thinner of the threads - I usually use embroidery thread.  

My notes  on when I used it for quilting with my 12000:
Blue bobbin case
50 wt cotton in bobbin
100# Microquilter poly (Superior's) on top
HL stitch #1
SL 2.7
TT 9.6 
FP auto
80/20 batting
There's no mention of a particular needle, so I assume I must have used my usual for quilting: Schmetz Quilting #14
Hope it helps,
Jan

I seem to be doing something wrong but can't figure out what it is.   My tension seems fine for regular sewing.  When I try to use the hand-look stitches with Superior's Mono poly on the top and anywhere from 50-30 wt in the bobbin, I can't get the bobbin thread to pull to the top.  I have adjusted my top tension up to 10 and am using the blue dot case after also trying the red but that isn't making much of a difference.  I am going at the slowest speed.  If I use stabilizer backed quilting cotton I get an almost okay result but nothing seems to work well.  Of course I've cleaned my machine from top to toe, flossed,  and turned it off and on a few times and tried several different needles as well. 
I just tried to work it out on my M7050 which I bought for classes but it's "contour stitch" wouldn't do it either which makes me suspect I'm the problem.
I would appreciate any advice.  Going to my dealer is out of the question due to travel restrictions at this time.
Thanks,
Ceil