RBW amp fail at 1 Khz. I made the crystal shorts and went through calibration but the filter wont adjust out like the image shows in the service manual. i.e. there is a sharp peak and not a smooth butterworth type of curve. Any suggestions? I am wondering about a bad PIN diode. I ran a NANOVNA on the crystals and can see them at 21.4 MHz but now the unit is saying that there is too much noise in the bandwidth and I am now getting RBW amp fail.