You can feed the 30MHz -10dBm signal back to the spectrum and measure, but this time vary the input attenuation,if the spectrum measures correctly on a different attenuation, likely the attenuator have a blown pad.
Or set the input attenuation to 0 dB, this should connect the signal directly to the frontend bypassing the attenuator, if it measures correctly, likely attenuator is dead if it measures bad, the next stage is bad
On my R&S FSEB, sometimes the mechanical attenuator relay gets sticky creating bad contact, so just varying the input attenuator setting, to make multiple contacts usually solves it