The old AC motors have two sintered bearings. If they have dried out then they can be oiled but they won’t be the same as before they dried out, you might get a year or two before they will need doing again. You really need to strip the motor down to lubricate it because if you oil it from the top, it could make the motor noisy, as you will be lubricating the series of washers on the top of the motor and they can then begin to vibrate. You can try using something thin like ZX1 or WD40.
The best thing would be to send it Michell , so they can then replace the washers and circlip etc. and give it a good clean out and lubrication.
If you are using a QC power supply with it, make sure you turn the QC off when not in use. The QC has a current path to keep the motor warm, over a long period of time this will speed up the bearings drying out. received from MIchell engineering in 2019