I think the trap on my mom's house's main drain line is clogged. It's a 4" J(?) trap just before the drain exits the house. I got the top off, but now I'm not sure what to clean the trap with! My 1/4" snake seems too small and my 3/8" drum snake seems too rigid to make the bend.
BTW this trap looks like a P trap except the clean out is on top. It's cast-iron, probably from the 1930s or before.
Also, I'm probably in trouble because I had to cut the cap off & I doubt I could buy a match. Could I get away with a test plug?