oher thing you have to chec is the check valve that valve left the water come into the air pump that will cause that the pump stop working again , but dont buy another is easy to make it work again send or left a comment here and I will tell you what to do.
thanks and let me know if you have questions i just learning English, just in case you see weak my post . t
this is the relay next to the air pump check the wires coming out from there, normally is the withe one.