Hi, Ride to Live, the golden rule of cylinder mowers is this: Reel mowers are expensive to run and maintain....bearings are cheap (by comparison) so, if in doubt replace the bearings.
By this, I mean , if you don't know the history of your SB, and you don't know what bearings have been replaced and (more importantly when)....replace them. they are cheap by comparison of the heartache you will (and dollars) feel if they fail...usually at the most inconvenient time.
To assess them is a matter of experience and feel...it is hard to explain...unless they are really shot...therefore my recommendation to replace if in doubt....that way you can't go wrong.
