There should be a fuel filter that flops around in the tank on the end of the fuel line. Fish it out with a piece of bent wire and blow it out with carb cleaner. That should get it unclogged enough for the engine to run for awhile.

Quite possible your bud had water in his gas tank, try emptying the tank into a clear glass container and see what you see. Pump the purge primer to clear water from the carb.

Did your neighbor use straight gas?? That would kill it pretty quickly.

I would try cleaning if first. I have done this several times without having to buy are rebuild kit. most all the parts except the diaphram can be reused IMO. I have found the diaphram with years of use my looses it unseating ability and may not regulate the fuel properly. Most likely it plugged up or the fuel hoses have cracked and sucking air.