Wearing the rails and blowing the nose's sprocket come usually close in time for my 150T. One or the other, but when one goes, the other is very short behind. For example, it isn't worth the time to dress the bar as the sprocket is near to its end anyway. Or the reverse.
What I noticed, is that the bearing doesn't blow suddenly for no reason, but there's a precursor clue showing up progressively :
The inner race of the bearing is just a small steel washer held in place by the aluminum rivet, which one holds tight too the two flanges of the bar. When new, the external ends of the aluminum rivet are very slightly domed , easy to see on the nose's sides. With the use, the rivet's ends wear flatter and flatter, until they look almost concave. You would argue that there's no reason to become concave just by wear in the wood's kerf and you would be right. What's going on here is the rivet's edges become too thin to stand the side load of the flanges/ side plates. Under the pressure, the rivet's edges begin to fold toward the outside. It's like a lip of less than 1 mm wide around the rivet, showing at first at the tip, giving this concave look. That means the rivet comes a bit lose and the flanges start opening slightly, giving more side play to the sprocket and its bearing. Not good, as it increases the side load. Soon after that, you will be abble to turn the rivet between the thumb and the index finger. The end is in the near future. Insist a little more and the tinny lip on the rivet starts separating by an arc cut. Next thing you know, is the flanges spread apart and send away the tinny rollers of the bearing. Dead.
I thought to replace the aluminum rivet by a steel one. It should hold way better, but it hardly worths the trouble, as the bar's life is very limited by the rails wear.
Oh, I still can't post a pic, sorry.
