You take the feet, feed dog and throat plate off the machine so only the needle and the hook are left. This allows you to time the hook to the needle by hand. The hook should be very close to the needle without touching it. I believe you go to bottom dead center with the needle and then up 3/32" and needle should be timed at that point. Distance of hook point from needle should be about the width of a paper business card. Keep in mind the needle deflector will push needle from left to right before hook arrives. I also tell people to deepen the slot on the underside of the throat plate a few thousands so that #138 thread can pass freely over the bobbin case finger. Buffing the slot will also let thread pass more easily in the slot.
glenn