Nice, my favorite spectrum analyzer
Since you are opening it up, Here are something that will be useful, its useful for all FSxx series.
1. If the unit has a blue panel design (there is a red panel, this is the older version), first of all change the 2x 47uf aluminium electrolyte capacitor on the back light inverter, it sitting on the LCD, after years of running the caps are dry and this will drive the FET to a temperature so high that it will melt the solder and shift the inductor on the other side of the board, causing the LCD back-light to die.
2.The IF Filter module, change all the smd aluminium electrolyte capacitor. The ESR will be high
3. Power Supply Module, the main capacitor is tied using a cable tie, and I have noticed, they go brittle and causes the cap soldering to become loose over time, so if possible change the cable tie, but its a real pain in the ass to open and power supply module.