I'm not positive about this, but if your vents are smaller now than they
were 3-4 weeks ago, I'm thinking either one of two things:

you're right that the shunt was failing anyway, and the change in vents
means the pressure is going down.

or

you're (possibly) draining too fast (overdraining) and it could be a sign
of the beginnings of slit ventricle syndrome.

But, I'm really just guessing, here.

I can relate to the "feeling like a whole person" because when my shunt
was blocked and the NS tapped the shunt, it was like a weight was off
of my head. I felt so much better after that!