My washing machine is about 20 years old; I changed the carbon brushes for the second time recently (they last about 7 years); everything else seems fine and I

My washing machine is about 20 years old; I changed the carbon brushes for the second time recently (they last about 7 years); everything else seems fine and I hope the machine will last forever. It's just a drum with a big electric motor, a valve for water in, another for water out.