Petter M Victory fuel leak

Picked up a tidy Petter M engine a couple of weeks back. Ran OK after being laid up for a few years - but it has subsequently started losing fuel from the carburettor, it spits out from around the little brass pin to the left.
I can’t see any obvious reason for this - would a punctured/split diaphragm situated on the front of the crankcase cause this? I’m keen not to take bits apart from this engine as it is nicely painted!

Many thanks for any help or pointers you can give.

It COULD be a pin hole in the diaphragm but in all honesty it is probably now about to run out of fuel, I have  a Victory and 5 other M types and they all blow fuel past the drain rod when they are running low on fuel in the base tank.

Yes......you were quite right - the engine was running low on fuel. Thank you!