[georgehutchison]

did you takes the gearbox apart? if you put screws in the wrong place in the mechbox case it will cause the whole thing to be out of line and the hop up will not be straight. A worn tapplet plate will not pull back the feeding noosle enough and cause mis feed. The grinding sounds like the alignment of the motor to mechbox. sounds loose and needs to be tightened. check to see through the magwell that the mech box is straight and exactly in the middle of the metal body. if not there is a reason why and you must find it. hope this helps.