I watched my local garage change the tyres on my Roadster, about three years ago. The tyre bead nipped the sealant on four out of five wheels, despite the fitter being really careful. He had some dark grey silicon sealer, which he applied after removing the flaps of disturbed sealant, and we left it overnight to cure. It was such a good match that it was hard to tell where the repairs had been made. Since then there have been no leaks.
If you turn the spoke nut it will twist the sealer and crack it just enough to allow a slow leak.
The recommended way is to send the wheels back to MWS for a full reseal, but I decided to use the method above.
