Replace Vibrator motor of S5 as vibration is a bit weak

hi there,

we have 2 S5's in the house, one is mine and one my wife's .... now i noticed that my phone has a weaker vibration that my wife's - they have been bought the very same day, around 1 month ago from today, I was wondering how complicated it is to replace the vibrator motor..

basically mine at the max setting, for the "haptic feedback" is just as my wife's 2 steps below the max level, her phone really makes a bigger vibration when you click "back" or any key pretty much.

however when the phone rings or i get a message is less noticeable. the haptic feedback slider is the most noticeable.

i went to a Samsung's repair centre and they said they cannot repair it as it is now because it is effectively working, even though not as strong as my wife's.

What are your thoughts? is there some trick to see if it becomes stronger? i tried to tighten the screws on the back, it seems to have worked a little but nothing significant.

also, is there a chance that if i buy a new vibrator off ebay or amazon, it will not be as strong as my wife's again, so it will be just like the one i have now? I have just seen the guide on how to tear it apart and it seems quite lengthy so i am not sure it's worth it..

many thanks,

Gabrio