Receptacle tester shows all lights on
"Two dimly lit" means the wire between the dim lights is connected to nothing.  

If the center one is solid, that means hot-neutral are good and ground is missing.  If the side yellow is solid, that means neutral is broke. 

Make very sure all your grounds go back to the main service panel. It is allowable to retrofit just a ground wire if one is missing. 

Do not connect an isolated group of grounds together; I call that an "island of grounds", and all that does is spread around the hurt.  If one of them ground-faults, then instead of just that appliance chassis being electrified, the shock is spread around to every connected ground on the island, so you are getting nailed by touching cover plate screws, any piece of equipment, even conduit.