The most common cause I see
The most common cause I see for problems cutting glass is the work table being the wrong height (usually too high).
When you score glass your shoulder should be over the glass. This allows for much better control of the downward pressure. When the table is too high then you are forced to reach forward and, arm extended, try to create downward pressure.
I can’t tell you how many times I’ve seen someone improve their cutting skills 300% just by putting a 4″ platform stool under their feet.
Helios Kiln Glass Studio