I picked up a used DW 788, with the stand and worklight, and am having an issue with some "knocking" if I advance the speed past about 1/2 way on the dial. I also can get the noise when I advance the tension beyond about 3.5, leaving the speed at the mid-setting.
I took off the switch/cover, and did the "fix" where you slightly file the underside "hump" on the tension rod cover. I also did the suggested adjustment of the tension rod, by rotating it one turn counterclockwise, then, when that did not fix the issue, I did another 1 turn. Still have the "knocking" noise and before I tear it apart, I wondered what I need to look for next.
The blade was the only one that came with it, which appears to be about a No. 3, reverse tooth, and whoever had the saw knew about lightly scuffing the blade ends, as they were obviously done that way. I have an assortment of Flying Dutchman blades on the way, but the "knocking" is not gonna be fixed by new blades. I bought a foot switch, and the saw cut fine, although in 1/2" baltic birch, I could tell the blade has seen quite a bit of use.
Any other help/tips are appreciated. I'm a novice at this scrollsawing.