That gunky covered thing in the sprocket well appears to be fibreglass, probably put there as a bodge it fix when the chain snapped, quite what it was meant to achieve there I'm not sure, the only benefit would appear to be muck proofing the cam belt and generator..
I can either extend the metal separator on the crankcase to cover the gap or I can rebuild it with a chemical metal compound, neither will prevent damage if the chain were to break again but it may keep the grime out of the generator area a bit more effectively than loosely packed fibreglass matt held in with congealed chain lube.