You can also buy washing machine parts from a bricks and mortar store - if you can find one nearby. You will often have to end up ordering it at the store and then going back to collect it when it finally arrives, as many stores do not keep any but the most common parts now. They do this to reduce their own costs as it is no point them carrying a lot of parts that may well not be needed. They could sit on the shelf for years until that model appliance went out of date and then they would never get sold.
Many chemicals both in the detergents and possibly in water can cause damages to the machine. There are some other problems like hosepipes or other fittings getting loosened in the course of time. Improper electrical connections can also cause damages to the machine. No one can predict the problems that may occur due to moisture, heat, chemicals and electricity. Overloading of clothes also can cause damage to the machine.