troubleshooting Sewing machine trouble

[Northmount]

Just a point of clarification.  The needle direction for a zigzag machine is with the groove facing the front of the machine.  Has to be that way for the hook to pick up the thread as it zigzags.  If the angle is off, it may drop stitches only on one or both sides while doing a zigzag stitch.  If the needle is positioned with the groove on the left, it is highly unlikely for the hook to pickup the needle thread.  And if it does, it's likely to bind up in a couple stitches and make a bird's nest under the needle plate and around the bobbin.  Don't ask how I know.

There are some posts here about selection of the correct needle size for thread.  One method described is to take about a yard of thread, thread it through a needle (not in the machine!).  When holding the thread at a diagonal, the needle should be able to slide down the thread.  If it won't it has too small an eye.

Tom