I have a vintage 1958 dated Rex Monaco 2-stroke moped in good working condition but which is very slowly leaking oil from the gearbox. The chances are that it never had any seals replaced in its working life (it still had it original spark plug when I got it) and since it isn't one of the mainstream or classic brands the chance of finding an original or reproduction gasket or seal set for the engine case is slim to none (and I have tried). One though was to cut out a gasket manually from sheet of appropriate gasket material but I was also thinking of using a curing sealant like Curil or Curil T to do the job. Any recommendations? The manual 3 gear shift took a bit of getting used to but it's great fun for pootling about in the valley.