When working on the A4 assy. the ONLY adjustments you should make are: - Cavity frequency, unscrew locking ring and while looking at the A7 J1 signal or 2nd harmonic reading adjust for max and then lock down. - Attenuator, Unlock with allen, adjust for same, usually pulled all the way out. Remember to lock. -S5 the one by the attenuator, only needed if tube swapped but if you adjust make sure the peak does not slip when you tighten the locknut. - the top pot, adjust for the same. - If you adjust any of the other locknutted plungers you will NEVER get back to where you need to be!!!! Cheers, Corby