Many Whirlpool built Roper dryers ( there may be other brand names ) have a "slide" to keep tension of the drum belt instead of the wheel on the bracket like the older ones did.. This slide has given troubles of being noisy, grinding away at the belt and wrecking the belt, #53.....
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If the tension slide gives you problems...it can be removed and the more reliable....
....older style idler pulley can be installed in it's place.