Serious mechanics will disdain this field-fix, but it works and can save the day when storm clouds are on the horizon, a bearing has spun on a shaft, and there's still 10 acres to bale, or spray, or whatever.
If the failed bearing has spun on its shaft and reduced its diameter, use a hammer and center punch to pock the worn area of the shaft with dozens, maybe hundreds, of small craters. Make that area look like it's been knurled. The raised edges of all those craters can increase the shaft's diameter enough to allow a replacement bearing to temporarily fit snugly.
This isn't a permanent fix, and I'm reluctant to confess that I might have been party to such crude repairs on occasion. But sometimes my job is to make the customer happy, at least temporarily, and not to make time-consuming permanent repairs.
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