Antennas....
There is no perfect antenna. If it's supposed to be omnidirectional or directional or whatever....it's not perfect. Whatever antenna you have, it'll have undesired lobes. (In this case, we're talking about the
glide slope transmitter antenna.)
BelArgUSA is totally correct in his method. Not only will this circumvent
tracking one of these undesired lobes, it also usually keeps you from hitting mountains.
Your company's SOPs should address this issue. If not, the manufacturer of your aircraft should have a procedure for such a situation.
Fly Safe,
PantLoad