I had to replace the bearing seals a second time in three years. When I got the tub disconnected from the housing with too much banging required I saw that the spider assembly had corroded badly and only one arm was fully affixed after two arms had cracked. It's unclear how many were fully cracked before all the banging but I expect at least one was cracked and let to the bearings having a rough time.
It's impressive that the spider arm lasted 12 years as there is a stainless to aluminum (?) connection that I'm confident breeds a minimal electrical charge that sets up the corrosion. I'm guessing some rubber would have helped that.
Either way, I would rate this fix as 4 hours if you know what you are doing and don't spend too much time cleaning along the way. The YouTube videos make it very doable for a handyman but it is going to go quickly for anyone investing the time to do it right.