if it sounds rough then can be bearings, brushes / commutator, or the fan plate (or whatever it's real name is) seen these near blocked before.
remove ball assembly via 4 torx screws, side cover 3 torx, then another torx under that, disconnect black and white spaded cables. onto other side remove central torx screw and inset - then at an angle remove motor in its housing from plastic sleeve bearing side first. bit awkward if you haven't done one before.
Inspect motor and decide what the problem is.
head beater non function
check with voltmeter set to ac~ 250v and above range. check for mains supply behind side cover with the 3 torx - it's the red on the microswitch and the white wire with the thinner spade.
If not there then it can be switch in main assembly or the cut out switch can burn out, if it is there and you can confirm mains voltage is present at the beater motor then the head motor may have failed.
the 1 ohm wire wound resistor can blow on the sub pcb in the head too, check it with a meter set to ohms.
If resistor is open circuit, then this is usually down to head motor failure
Take care working with live electrics.