Stihl 015 Problem

Recently I inherited a Stihl 015 chainsaw that had sat up for a long time. I dumped the old gas out and refilled with fresh gas. The saw started and ran for about 4 minutes and then it died. Since then it has made no effort what so ever to start again. I pulled the side cover off and squirted a small amount of gas into the carburetor and it started immediately and ran for about 3 seconds. At that point I removed the fuel line from the carburetor. With the saw sitting upright and a full tank of gas, there was no gas coming out of the line. I could hold the end of the fuel line lower than the saw and some fuel would slowly drip out. I have not been able to find any instructions on how to remove the fuel filter to see if it is clogged. I did back flush the fuel line with some carburetor cleaner, but it didn't seem to help. So, as a chain saw neophyte, should I see fuel run out of the line when it is disconnected? Since it does run when fuel is squirted directly into to carburetor, is it more likely that the carburetor is plugged? Because this is an old saw, but almost never used, and finding parts seems to be a bear, I don't want to disassemble more than I have to before having a decent idea where the problem is. Thanks for any assistance!