Hi I have an old root manufacturing chainsaw model R 576 with a clinton engine. I'm trying to figure out the fuel routing. The engine fires up if gas is poured into the choke area. I had to clean out the fuel tank as it was plugged with varnish. I noticed the bottom fitting hose goes to a fuel filter (looking) capsule which is attached to the carb. The bottom of this capsule has a nipple cap which has another hose running to the bottom of the engine. The fuel never seemed to come through to the carb so I removed the cap/ nipple and out popped a spring, disc and diaphram. I may have lost some other parts in the process. Could someone please explain what do I have here and can I purchase new equivalent parts for this.