ffkiwi

These engines are not noted for their longevity......! Where is it bleeding fuel from?-around the carb spigot or from the front bearing? If the latter then accept that it is clapped-and there's nothing you can do about it. [Well you actually can-.......you could buy a replacement crankcase......if you could find one, or have a very good engine man replace the crankcase bushing-BUT either option will cost you more than the engine is worth]
If it is leaking from the carb-again you need to determine exactly where-and why. The carb could simply be loose in the crankcase-though in that case I would expect you to have trouble maintaining even running-tighten the securing screws. If it is leaking around the spigot then a replacement O-ring should solve the problem. If it is leaking around the barrel then you need to check why-scoring from dirt or debris perhaps. Carb barrels and bodies can be replaced-but if a barrel is scored then the body is likely to be scored as well. A complete replacement carb will once again run you more than the engine is probably worth.
Finally-is the needle valve assembly properly threaded into the carb body and the lock nut tightened?

First determine the source of the fuel leak, then you can make some decisions.

ChrisM
'ffkiwi'