gramma nancy

I am always so impressed with the knowledge and helpfulness expressed by the denizens of this board. Now it's my turn to ask for help.

I pulled my featherweight out today after not using it for more than a year. It is in great shape and has never had any problems. I began piecing with it and it may as well have had a ruffler on it. The stitches are straight and even, but they pucker the fabric terribly. The problem can't be ironed out. It has to be ripped. What is going on?

I rethreaded both machine and bobbin several times to no avail. I tried changing the stitch length, but it had no effect. I don't know what else to try.

Any ideas?

Thanks for your help!