Your problem is the cam gear on selector. Open machine by removing single screw from back of machine under carry handle. Lift handle and remove screw. Back has to be pryed slightly from machine and lifted off 4 slide pins. You will see black round cam. On it you will see a lockdown lever that holds cam when stitch is selected. That lever is binding on shaft. Put oil on both sides(top and bottom) and pry it up and down to work oil on shaft to lube it. May take multiple applications of oil. When lever moves freely when stitch selector is operated then it will properly function on stitches. Reverse to reassemble.
Bruce, March 2015