Worry?
You don't say if you have attempted to use the machine and if so what the bearings sound like if it runs or whether the brushroll rotates freely etc?
Nine times out of ten on Hoovers I dismantle the agitators and regrease the bearings using a special grease gun. This also affords me the opportunity to remove any build up of threads that might stall the machine, check the presence/location of the thrust washers and to free off the sweeping brushes! However, in some cases, the bearings can be seized solid in the housings, which are usually rivetted onto the main agitator shell. On occasion I've had to resort to heat to remove the remains of a bearing shell after driving the shaft out of the housing. On the other hand, you may be luckier if the agitator has been regulary serviced.
As for the motor I would exercise discretion; it may not be worth dismantling unless it sounds rough, especially if you're not going to use it much. Ball bearings are used top and bottom (on the 450), which can usually be regreased unless in a bad way.
Stephen