Barnett Quad 400 Crossbow

When looking at the yellow part of string where arrow goes in, one side is 3 inches and the other side is 4 inches long. This happens when cocked or uncocked, looks like the string could be pulling to one side and I cannot get arrows to shoot a pattern. Completely missed two deer so far and lost two due to bad hits. I had a horton but could not get parts for it but I never missed with the Horton. Beginning to believe something is wrong with bow. Can I remove that plastic piece holding the strings apart? What could be wrong?

I purchased my Quad 400 last fall 2014. Having read all the bad and scary reviews I was wondering if most of the problems were with older models? Has the product improved with the newer models? Do other Crossbows have similar issues?