I've ordered C0G/NP0 caps to replace all polystyren. Will desolder them, clean the board and then solder the ceramic ones...Polystyrene has a 240°C melting point, and is susceptible to solvents. Try out on a styrofoam cup
As these caps are often not potted, or use metallized foil, but use metal foil, alternate with polystyrene film, liquids may enter between the layers, the cap may have kicked the bucket.
470pF, 5pF and 15pF are present in the WA84. I've also ordered 1uF and 4,7uF in Nichicon Fine Gold to try instead of those tantalums
