I would try too see what’s happening when actualy sewing with tread and material (leather, canvas or what you are using)
It can be hard to see, but if you can, and turn the machine by hand, you can see what is the problem
if the machine forms a good loop in the thread the hook needle distance is not that important
but if your thread is bad or the timing wrong you might get this.
with some machines you can see it by sewing on the edge of your project and open the slide right of the needle
sometimes you have to look from the underside.
use a flashlight!