STEP 4: INSTALLING THE TIMING BELT. Check for severe cracks or missing teeth and replace if necessary. Place the timing belt around the 2 sprockets (left and right gears) and then install the belt tensioner but do not tighten too much the screw yet. Now turn the white plastic belly in the belt tensioner to adjust the timing belt so it is not too tight or too loose (you should be able to depress it about 1/2"). Now finish tightening the screw holding the belt tensioner just so the white plastic belly does not turn.
STEP 5: THE NEEDLE POSITION. First just loosen (do not remove) the 2 little screws in the left sprocket body. You need a small hexagonal screwdriver tip but you may try a narrow enough flat screwdriver to loosen them. The goal is to be able to move the rotating hook freely in order to synchronize the rotating hook with the needle position. In other words, we now need the rotating hook NOT to move while we turn the hand wheel and move the needle to its exact position.
DO NOT lower the needle yet as it could hit the rotating hook. Just position the needle by turning the hand wheel TOWARDS YOU so the needle comes slightly over the needle plate opening.
Move and center the needle position lever and make sure the needle is also set in the center position. If the lever does not seem to work fine loose the lever mounting screw so you can freely pull or push the needle position lever to set the needle in the center and then re-tighten the lever mounting screw.
STEP 6: SYNCHRONIZING NEEDLE AND ROTATING HOOK. Turn the rotating hook by hand so the hook or sharp tip point in the rotating hook wall faces the back of the machine. Then, turn the hand wheel SLOWLY TOWARDS YOU so the needle goes completely down. You should be able to see the upper and lower timing marks (grooves) appear on the needle bar when the needle is all the way down.
When you see the upper timing mark flush (even) with the machine body the needle is at its lowest position. Make sure the rotating hook tip is still facing the back of the machine and in front of the needle or otherwise hand turn the rotating hook as necessary.
We are now just 3/32 of an inch from synchronizing the needle. Fix your eyes on the timing marks (grooves) and continue turning the hand wheel VERY SLOWLY TOWARDS YOU so the needle and the needle bar raise 3/32 of an inch which is when the upper timing mark disappears and the lower timing mark is flush with the machine body. Make sure the rotary hook tip point is still in front of the needle. Now very carefully (so nothing moves out of position) tighten the bottom sprocket little screws. Re-check the hook tip point and timing mark position. Test the setting by making a few revolutions of the hand wheel to be sure the needle does not hit any part of the rotating hook.
THE ROTATING HOOK AND NEEDLE ARE NOW SYNCHRONIZED !!! 
We are now ready to lubricate the machine, reassemble the panels and do a real sewing test. 