it could be the clutch plate/sprocket is slightly bent, or even the shaft running from the clutch housing to the sprocket.
it should be a simple matter to see which item is bent, simply turn the reel by hand, and see which sprocket doesnt stay dead centre.
for the actual bearing, just try to move the reel up and down, looking at the blades touching the bedknife, if the blades move up and down, then new bearings it is.
