Machine Quilting - Finishing Up

Yesterday I tried machine quilting for the first time... I used a walking foot and did straight lines and that didn't work out so well.  After ripping those stitches out I knew I had to do something different so I tried free motion quilting using the stippling design.  At first that didn't work out well at all, once I got started going good the thread would break... so I thought it was a tension issue, and it wasn't.  So after a few hours of that I decided to try a different machine and WOW!!!  It worked like a charm!!!  So I am still not sure what the problem was with the first machine (my very old Kenmore rescued from the Goodwill store) but my other machine (brand new Singer) worked like a champ... that's funny cause my Kenmore aka Shirley, always gets the job done, but not this time...