Since you suspect other vac leaks, I think you made the right choice taking the car to the MB Indy because he should be familiar with diagnosing the vac leaks easily and accurately.

If it is more than just the booster then having it at a MB Indy could be a plus.

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1984 300D 398K-daily driver
1998 Honda Accord 102K -wife's daily driver
1991 Volvo 740 289K
2000 Toyota Corolla 143K