Odor in 2nd floor bathroom
We just purchased a home that was built in the 70s. The second floor has 2 full baths and one on the first floor below that. All 3 bathrooms share the same main vent. The second floor guest bath has the strongest odor and the master bath has it slightly. The first floor bath has no odor.
Based on other posts we determined that there is a clog in the vent line. When the tube drains we hear gurgling as it goes down. We think it is only a partial block considering the water drains very quickly. We tried to snake the line from the roof, but still have the odor. Is it possible that the branch pipe coming from the smelliest bathroom has the clog instead of the main pipe? If so, what is the best way to unclog it?
Thanks
J