swisher rough cut pull behind mower

I have a 52" rough cut trail cutter swisher pull behind mower that I've had nothing but issues with lately. We just replaced bearings in the mower and put on a new belt & mowed one field just fine. The next time we used it the bearings completely seized up. We again changed them & then went to mow, I got one strip of the field done & boom the blades seized up & mower shut off immediately. The mower starts back up fine but, bearings are seized up so blades aren't able to engage. This is the first time we've ever had this issue with the mower and we've had it for years. I got the bearings directly from swisher. Everything else looks fine, I have no idea what else to do. Any suggestions?

Is it possible that there is a spacer between the bearings that is missing or damaged causing it to side load the bearings when everything is tightened down.

we put everything back together by manual cause we bought a new driver housing. Is it possible we're putting the whole kit on too tight, could that be causing it to seize up? Is there a certain torque it should be tightened down to?

I recently ordered a new belt for my trail mower. I ordered what it said was the part number from the owner’s manual. Could not get it to fit. So I sent an email to the parts department and they said that was the wrong part number. If you are ordering what is in the owner’s manual it could be the wrong part number. You might want to check with their parts department and check if that is the right part.

Only 3 reasons why bearing sieze in spindle housings
1) no grease
2) out of alignment
3) Missing spacer crushing the bearing