In my experience they usually start making odd noises and stuff when they're on their last legs. It CAN be that the bearing is scratched and creating friction, you never know.
It's pretty easy to take off the intake tube and check it though. There should be NO in out play, there is some side to side and up down play because of the bearing having a slightly bigger bore then the shaft diameter, for the oil film, it's not a lot though.
It could be leaking up pipes or a boost leak somewhere too.