My house has two stories and its two toilets have been having all of
the symptoms of a clogged vent pipe. Some of the symptoms have been:
the toilets flush slowly and very inefficiently, sometimes the bowls
fill with water before flushing down, and after flushing the water
often do not recover to their prior height in the bowls. I plan to
go to the roof of my house to rotor out the drain with a 25' x 3/8'
cable that I bought for this purpose. Here are my questions:

1. Is the vent pipe which appears on the roof a direct extension of
the pipe that drains the toilet? In other words, when I clean out
the vent pipe, I am mainly cleaning out the sewer pipe from the
toilets, sinks and bathtubs?

2. If #1 is true, it wouldn't seem possible that the pipe would be
clogged below the second floor toilet. I am assuming this since I am
having problems with the second floor toilet.

I would appreciate your thoughts about this.

Thanks, Al Kondo