Isn't there a magic black box you can plug the ILS receiver in to to check the proper electronic functioning of the system and indications? If they check out OK then the pitch servo theory comes next (assuming it's an aircraft type that has a dedicated pitch servo). Assuming the guys flying it know the magic number TQ reduction at top of drop that gets you on a pretty good GP all the way down without touching anything. Certainly in the S76 with SPZ7600, if you decouple the collective mode, the proper manual power reduction at the top of drop should have you on the GP all the way down without having to touch anything....maybe just a click or 2 of pitch trim every now and then.