Eaiest way to check the mower deck bearings is to take off the belts, and just spin each spindle to see if it's making noise. Usually the mower deck bearing will be noisy all the time though, and they can be that way for quite a while before they come apart. If the tractor is feeling labored under load you may want to make sure your plugs are new and gapped correctly, fuel filter is new, and maybe put some gas additive in your tank to clean up any deposits in the carb.
Rattosh51
YT6800