I have a 788 that is just about a year old.. What I find is that speed past says 6, it gets pretty loud.. Not sure if it's the knocking issue or not, but it sounds more like it's not in the front of the saw, but more in the back.
Also, I use a foot switch when sawing. But seems that every time I'm done with a cut, when I go to lift the upper arm up, I have to tap the foot switch to make the blade arms move just a bit, then it lifts up all the way. Otherwise it only lifts up like 3/4 of the way.
Anyone got an idea on what is causing this?