My basement toilet has worked fine for a the last decade. Recently, we noticed it was draining quite slow and was bubbling when the washing machine (on the same floor) was running.
Had a plumber out and they augured both the toilet and the clean-out finding no blockages and the problem remained.
We then found that by removing the studor vent on the run next this toilet allowed the toilet to flush properly. Given this, we thought maybe the studor vent was bad - but after replacing with a new one, no change in behavior.
I'm wondering if anyone has any ideas of how to continue troubleshooting?
Note and possibly unrelated: There had been no plumbing changes/updates in the house prior to this behavior other than recently having the kitchen sink on the floor above augured to remove blockage due to garbage disposal build up.