That's actually a bowl drain valve, and the rubber seal deteriorates with time, of course.

Replacement kits are available; https://www.outdoorking-forum.com.au/engines...gine/tecumseh-walbro-bowl-drain-assembly

Usually, all you really need is the seal, but I don't know of a local source for those.
Plenty available ex the US though; Tecumseh P/No 27554.

Cheers,
Gadge

"ODK Mods can explain it to you, but they can't understand it for you..."

"Crazy can be medicated, ignorance can be educated - but there is no cure for stupid..."