I had a made-in-Taiwan Sears Craftsman model 351.22632 3-wheel (triangle) belt sander/grinder that takes a 1" by 42" belt, which was bought used in 2009. This unit worked in the sense that it makes sparks and removes metal, but it vibrates badly and is noisy. The 8" sanding disk wobbles so badly as to make it useless. Nor is it possible to get everything level, square, and perpendicular, so I can see why it was never properly adjusted.
The drive pulley that accepts the drive belt from the 1/3 HP motor kept creeping off the shaft until it ran into the belt cover (polystyrene), and melted a track into the cover, making bad noise and bad smell. The problems are built in by design.
In June 2015, I saw an older Sears Craftsman 351.22610 4-wheel (triangle) belt sander/grinder that also takes a 1" by 42" belt, and is a direct clone of the Rockwell 4-wheel belt grinders. The closest Sears equivalent to 351.22610 (no longer listed) is 113.22560 with the8" disk sander attachment.
The 351.22610 (4-wheel) unit ran somewhat better than the 351.22632 (3-wheel) unit, but still needed improvement.
It turns out that the biggest cause of vibration is that the various flat-belt pulleys were left as cast, and are far from true, both wobbling and being very eccentric.
Made up some special-purpose arbors to hold the pulleys in my lathe (Clausing 5914), and machined the crowns so the belt would run true. This helped a great deal, but given the lack of reference surfaces, wasn't exact on the 4" ball-bearing idler pulley. (The 4" drive pulley and the 2" idler pulleys came out far better, because the reference was easily found.) I'll probably end up making a new ball-bearing idler pulley from 6061.
The old Delta/Rockwell units (model 31-352, Vintage Machines document number 5853) are no longer made, and the old ones are treasured.