I have a M&P 2.0 metal competitor and noticed that no light was getting to the end of the sight. The sight has three channels (one on the top and one one each side) but very little light gets to the end to the point that it looks black and not green. This sight does not have and opening in the front like most.I did try cleaning the tube on each side and no change but there was some light dirt. Has anyone heard of this and have a fix?