you sure thats where t's leaking from(the sump) tbh it's hard to see it's so dirty.the gasket sealant you can see does that if theres too much,i've fitted quite a few sumps recently,no paper gasket just liquid gasket,and if too much used it will squeeze out a bit,but they are mated so well you wont get it pissing out even if the seal fails.sump plug looks proper corroded.but from those pics still hard to see where it's come from as looks relatively dry around sump seal