I’m changing Testastretta cam belts for the first time. I’ve watched the CCW videos in preparation, and some others. Oddly enough, the marks from the previous cam belt change lined up almost, but not quite, perfectly. I marked the old belts to show precisely where they lined up on top of the u shaped mark the last mechanic drew on the belts, so in essence 2 of the 4 marks were 1/2 tooth off when the other side was spot on. Cycle Works belts were on it and that’s also what I bought. I counted the Belt teeth between the drive gear mark and the first cam mark , and marked the new belt. When I put on the vertical belt there was slack in the belt between the two gears which caused the cam mark to move CW off the mark when I attempted to tighten the belt. . Moving the belt back CCW one tooth on the drive lines up both the cam marks, with 19 tooth count from cam to cam. Of course then my count is off 1 tooth less less between the drive gear than last time. I left the vertical cylinder that way and went to the horizontal. I counted and duplicated the marks on the new belt. There were 20 teeth between cam marks. When I tried this with the new belt I had to go to 19 teeth between cams to get both sets of gears to line up at the same time. I assume this is a result of belt wear. Am I doing the right thing here ? I read that it’s always 19 teeth between cams, true or false ? At any rate, it is now. Comments , witty remarks , scathing criticism ?