If you have a leak on these mowers it's loud like having no muffler at all.
The muffler on the Victa 18 just uses one bolt to hold it on ,eBay sell the correct gaskets ,they are a thick gasket, sometimes the alloy on the muffler is warped where it bolts onto the port and they won't seal properly also check the end of the baffle is blocked as you get a lot of rusted out baffles.
As you tighten the bolt on the side of the barrel you need to push the muffler towards the base so that gasket can seal.
There is a metal plate under the alloy base and that gasket must be sealing also. It's not uncommon to find this metal plate cracked and leaking.
