Could you provide a description of the home? Single story or multiple story, # of square feet, open concept construction? Do these dead spots have anything in common? Distance to the R510, # of walls between the dead spot(s) and the R510, mirrored and/or tiled walls such as bathroom, stainless steel appliances and tile back splash like a kitchen, fireplace and chimney between you and the access point?
If the settings were left at default when installed I wouldn't expect a Ruckus R510 to have difficulty covering a normal size home.
There are free tools available that will allow you to see the signal level on a smart phone or a laptop. One of my favorites is Wi-Fi Scanner by Lizard Systems. They have a free personal license. A tool like Wi-Fi Scanner will also show you possible competing neighboring networks.
Eliminating signal issues, strength or interference, would be my first step.