90% of the plasters are broken (the plasters are plastic film of buttons). The reason for the bad is that when washing feet, the plasters get wet and seep into the plasters. After a long time, it will grow hairy and lead to power failure, so it will fail. (although you may be careful when using it)

Solution: If there is hair, tear off the patch and pick it up with a sewing needle at the edge of the patch, which has a 50% chance of recovery.

Ask again if you don't understand.