Sounds like the timming is off. Check your needles, change the needle frequently, if you are going to use the machine on a frame. Also the thread your using and the type of needle should mathch. Ask your repair man witch type of needle you should use for the type of thread your using.
I am a retired profesional seamstress who used a industrial quilting machine also. Are you using the machine on your quilting frame yet?
Happy Quilting!!!