I have noticed when I have it set to the left side of the dial, for 10 spi, at times when I double click the black button, it beeps and the stitching is quite smooth. At other times when I double click the black button, it does not beep, and the stitching is more "choppy" or jerky. Sometimes I can't seem to get it to "beep" even when I want the stitching to be smooth.
To start the PQ mode, you need to double click the black button. The first hit turns on the green RUN light. If the needle was down, it will be pulled up before the green light comes on. The second hit should come within half second after the green light was turned on. Practice the rythm of the double clicking by watching the green light. After getting the right timing learned, you will be able to do it without watching the light.
NOTE THAT BEGINNING WITH REV 1.0 OF THE I/S-TURBO, THE PRECISION MODE IS STARTED DIFFERENTLY: YOU SHOULD HOLD DOWN THE START SWITCH UNTIL YOU HEAR A BEEP. THE GREEN "RUN" LIGHT WILL START FLASHING SLOWLY, INDICATING THAT THE MACHINE IS RUNNING IN PRECISION MODE.