Torn gasket on kitchenaid KSB560MCO blender - KitchenAid KSB560 5 Speed Blender

It will either be the rubber gasket (it goes between the glass jar and the blade assy) or it could be a worn bearing/bush around the chopping blade shaft. Replace either the gasket or the blade assy.

Buy a new one

Are you sure you are installing the gasket correctly?

Leaks are usually the result of a misaligned or cross-threaded blender jar base or from the gasket being installed incorrectly. Make sure the gasket is installed between the blade assembly and the screw on base.

If this does not help, please reply or repost.

Why not just buy a new gasket? Your problem is very short on detail.

According to the illustrations at the link below, the blade/gear assembly is not replaceable:
Kitchenaid parts

Check for cracks in the bottom of the glass.If it continues leaking then the gasket is compressed and no matter if it visually looks good, cause it has lost their sealant skills. Replace the gasket

Make sure the blade assembly is put together in the correct order. The blade needs to go through the gasket so that the order is pitcher glass, gasket, and metal blade base. Then the final plastic cap threaded onto the pitcher. If the gasket is not between the pitcher and the metal blade assembly, you will have leaks.
Also, check the gasket to be sure it's not cracked and that it doesn't have residue on it.
I hope this helps. If it does, please come back and rate my suggestion!

The cutters are part of the collar itself and not available as a separate part. If there is anything wrong with them you need to replace the whole collar. The collars are available on Amazon UK, K A Parts as well as other places.

My Blender Model number KSB560MCO does not run. When try to blend all of red lights come one and they blink and move around. Any suggestions what could be wrong? Appreciate any help.
Thanks