I am not sure about using a peep sight with rubber tubing, but my Fletcher Tru Peep lines up great every time. In fact, if you adjust the string twist correctly, you don't even have to use the D Loop to line it up. It is perfect every time. It's all in the string twists. Usually a half or full twist will fix the problem. I would trash the rubber tubing, and go with a Tru Peep or SherzAPeep.