Sounds like the bearing is wallowing in it's stamped housing.
Don't think a new bearing will fix that.
I have eliminated those old style bearings and replaced them with the newer
taper Timken style bearing assy's much,much cheaper to replace, ( Lm 11949 and Lm 11910) (outer wheel bearings on older GM vehicles) but you have to change to the Aluminum housings also.
I was lucky as I had a junk deck from a 1720 and just used those assemblies.
I didn't need any adaptors/spacers.
As far as using that deck for a "brush hog" they are aged and thin now-a-days and the spindles tend to bend the housing mounting area causing the "cut" to not be as nice/even as it was new, I'm sure. BTDT.
