I once repaired a vacuum dashpod with a bicycle tire patch. But the surface of these are ribbed, which makes them more difficult to patch. If you can find a realy thin type of rubber patch, and just put alot of pressure on it when its glueing, it should seal. Or maybe just find some realy thin rubber, and super glue it over the rip.

__________________
1981 300SD 512k OM603