A little more info for reference the 3 main bearings in the belt setup are 6003RS. These bearings are a common model and you can pick up a set of 2 for $5.00 on fleabay. Original Japanese Koyo are also available for $9.00 each plus $20.00 postage from the U.K.
2 are located in the blade section and 1 in the tensioner. When I knocked the bearing out of the tensioner it was so wedged that the 2 small tac welds cracked which were barley even welded to the support bracket so I had to weld it back on.
That tension bearing seems to be a bad design even though it's a sealed bearing the cup the bearing sits in which the belt runs on gets burried with dirt.

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I've got a highway to mow