I've removed the covers to relays like that before. They aren't really intended to be removed, so its likely they will not snap back in place very well once you've cleaned the relay contacts.
IME cleaning relay contacts is problematic. When the contacts have got to the point that they are able to corrode, the relay is on borrowed time and you will find that the contacts will need service again, sooner rather than later. If you can find a replacement you are better off replacing the relay itself. IOW only clean the contacts when you have no other choice.
IME cleaning relay contacts is problematic. When the contacts have got to the point that they are able to corrode, the relay is on borrowed time and you will find that the contacts will need service again, sooner rather than later. If you can find a replacement you are better off replacing the relay itself. IOW only clean the contacts when you have no other choice.