Get the dealer to tell MMC that it was a standard Nitrile seal of whatever part number Morgan think it should be. Without pulling it all to bits again they will never know what is fitted. It is unlikely to leak and will be out of warranty if it does, so you can replace it yourself another time.
Just realised that it is because MMC don't do any parts for the Bevel Box, not the type of seal, sorry. Maybe list the next unit up, that being the bevel box? It will point to the stupidity of not doing any spare parts for large components such as the bevel box. It's like changing the engine if it needs a new rocker cover gasket almost.
Last edited by planenut; 20/04/21 10:13 PM.
