Thanks everyone. I always keep the same thread on top and on bobbin. I was using a variegated King Tut thread. Now using one color Isacord and it is better. I had not adjusted the speed control, didn't think of that. I usually keep it on about medium speed.
The dealer I took this machine to is the local retailer for the Juki and has been in business many years, I think the service dept. is alright, but the owner today suggested we might need to send my machine in for factory service. The technician last week was the one who suggested trying a different thread. I was hesitant to do so as so much ripping out involved. But now I am just going to finish this quilt with 2 different threads, and ....never use King Tut again.
Thanks so much for all your thoughts.