Atillio, the TG may be OK now, producing the right center frequency. You should be able to get the amplitude to peak at narrowest bandwidth, and drop off when the tracking pot goes either way from the peak. Once this is working right, nothing should change in the actual output signal level when you change the SA's IFBW. The amplitude response is then up to proper operation, and calibration of the SA's gain at each IFBW setting. I think each one is adjustable. First, be sure you're not the cause by running the sweep too fast for the BW, - the narrower it is, the slower you have to sweep. I think there's supposed to be a "UNCAL" warning if the SA setup is wrong, but not sure. Just be aware of the issue. If the amplitude response really is wrong or different between settings, then look at the 7L13's calibration.
Ed