Weak Flow, Smell, Vent Clog?

I have a toilet problem that has me stumped. I'd appreciate any help
you can offer.

I just moved into a town house a few weeks ago. There are four toilets,
and only the basement toilet has this problem. The flow of water during
flushing is substantially weaker than the other toilets.

In addition, there is an odd smell in the main floor bathroom. It's not
a fecal or urine smell. I can't quite place it, but I think it seems to
be a blend of a chlorine smell and a sweat-like smell.

I read something on the Toiletology 101 web site that indicated there
might be a clog in the vent pipes. It said that sometimes small animals
get stuck there.

I think it is only the main floor bathroom that has the smell, and the
basement bathroom that has the weak flush. Would this be consistent
with the animal-caught-in-the-vent-pipe theory? Maybe it's caught just
below the point at which the vent pipe vents the main floor toilet?

Thanks for any light you can shed.

- Keith

I think I would start with replacing the wax ring on the main bath toilet. As far as the basement one have you checked the water level in the tank? Are all the toilets the same? It is very difficult to compare the perfomances of different toilets. Depending on how it is piped, if a vent was clogged it usually would effect more than one fixture.