Does your 8568B have the internal 10MHz OCXO running? If not check the internal/external ref switch for the correct setting. If set to internal, check for 10 MHz at about -10 dBm at the rear 10 MHz port. If missing, put 10MHz at greater than -10 dBm into the ext ref port.
The 8568 will not run - giving some of the symptoms you listed. The internal system RF chain and a chunk of the digital electronics will not function without the 10 MHz. This is unlike the 8566 which runs off the internal 100MHz (locked to the 10 MHz).
Don Bitters
