Originally Posted by
jlhmnj
Is the motor OK or the machine a little gummed up? How does it run unthreaded? Does it hestitate on a straight stitch?
It could also be the wiring - the foot control - friction somewhere - is the motor cold - when did you oil the machine last - use Triflow or regular machine oil - if it has had 3-in-1 oil it could gum it up and cause some drag - if it is only hesitating on the zig zag there are a couple places that have to be kept cleaned and oiled.
http://www.quiltingboard.com/vintage...-t70011-2.html on the second page there is a real nice pic of the needle bar and where to oil it. Open the top of the machine, if you push on the part on the needle bar that make it zig zag and watch you can see the one on the other end - oil it too.