Have a close look at the end of the rod inside the booster that pushes the master, it may have a spacer washer under the tip.
![](https://airspeedparts.com/forums/proxy.php?request=http%3A%2F%2Fimages.thesamba.com%2Fvw%2Fgallery%2Fpix%2F930175.jpg&hash=ad13a61198f5e9cacfd837e634a5ed6fba64b815)
![](https://airspeedparts.com/forums/proxy.php?request=http%3A%2F%2Fimages.thesamba.com%2Fvw%2Fgallery%2Fpix%2F930173.jpg&hash=2b0ea6b6d289807cf2e7db6b98a744c29cd6b5a2)
![](https://airspeedparts.com/forums/proxy.php?request=http%3A%2F%2Fimages.thesamba.com%2Fvw%2Fgallery%2Fpix%2F930176.jpg&hash=52dfc3cdf1b3a6828c11e5cb3d930b56fffe4e81)
If it's already gone you'll either have to shorten the rod, or fabricate a steel shim to move the master away from the booster, that one's tricky since the master has to seal against the booster to maintain vacuum.