2000 SL500, M113 V-8 engine

I had my intake manifold split opened (because of significant vacuum leaks detected there) and re-sealed by professional mechanic. 4-5 months later I can hear vacuum leak sound in the area between MAF and back of intake manifold. So I pulled out my "pickle jar smoke machine" and I'm 99% sure the leak is at the back of Intake Manifold… at the split seal.

As I started to do some research on this I realized there is quite a bit of sealing internally, once the top is separated from the bottom. And it takes quite a skilled operator to re-seal everything properly. If external seal is not holding… what are possible ramifications if internals were done sloppily?

Another thing I discovered was silicon around Manifold to Engine gaskets… Why? If you just install manifold gaskets and torque the bolts properly why the f*** would you even put silicon there? Needless to say I lost confidence my shop is skilled enough to do this properly.

So, while this vacuum leak is not causing major problem yet, eventually it will and I'm considering my DIY options.

Can this center split be re-sealed one more time and could this be done without removing Manifold from the engine? How tricky would this job be?

If I do have to remove manifold… should I just bite the bullet and replace it with new one?