This never happens with straight sew models, or I haven't ever had to set hook timing on them but quite a few 319s I've bought have needed to be timed. The other thing that commonly causes it is some dim wit in the past has tried to adjust the hook timing thinking it will allow them to use 15x1 needles.
Here is the procedure to check and correct the timing:
Step 1: Remove the end plate (cover of the needle bar) and the needle plate (slide plate) and tilt the machine back. Needle should be in the central position. Remove the bobbin case.
Step 2: Move the hand wheel toward you until the needle has descended to its lowest point. Now you need to check the marks on the top of the needle bar:
|At the very bottom, the lines on needle bar and machine should line up|
Step 3: Move the hand wheel while looking at the needle bar marks. Stop when the lower needle bar mark lines up.
|Needle has started to rise a little|
|Hook is exactly behind the needle, and should almost be touching it.|
|Loosen (do not remove) the screws holding the bobbin drive to its shaft.|
I think this procedure is pretty important to know, even if you only have one machine. If you can't get the tension just right on your swing needle machine you can be fairly sure the hook timing has wandered a little.