[Slight problems] Advantest R3131A Spectrum Analyzer

9 kHz to 3 GHz. I'm selling this for a friend who doesn't want it anymore. It turns on and displays, all controls work and it is able to read signals but friend says the signal seems "low". Not sure if there's some filtering settings or something is wrong with the input connections but he doesn't have the proper signal generator that can generate the proper frequency range to test it. It's an older model so he doesn't think it's worth it to send it to the manufacturer for repair so he's just gonna buy a new one. Overall good mechanical condition If you want it for parts, or think you can fix it. Shoot me an offer! Price negotiable!!