Hey Guys, first post, sorry for a long one. I have a toilet that will only flush one out of maybe 20 tries. The history. Brand new house 4 years ago, about 2 years ago, out of the blue, toilet stops flushing. I know, this problem has gone on long enough, but its our ensuite so we've lived with just going #1 in it for a while. I'm a busy guy but its starting to bug me that this thing is winning. What I've done so far: - pulled the toilet and used a rigid see snake camera, no blockage as far as I could insert it - below the toilet has two 90's then Y's into the same drain shared with our main bath toilet which flushes like a champ - 5 gallon bucket of water poured down toilet, flushes like a champ, I have to believe there is NO blockage in the pipe - thought maybe the flush holes were blocked, coat hanger'd every one, all clear - took the tank of the toilet off, took a pic with my camera towards the front, all looks good - took flapper and put it in my main bath toilet, flushed like a champ still, both flappers have the same setting underneath, not sure what it means, maybe the float/drop rate? have to think the flapper isn't the problem - the overflow tube is clear all the way into the 3" flapper opening Now the only thing I can think of is somehow the water isn't going through the flapper fast enough to start the siphon? The only thing I notice with this toilet that doesn't happen on my other two, (all 3 toilet are the same, 1.6 gpf American Standard) is when you flush this one, water comes back up the overflow tube almost to the top and kind of gurgles then goes down the tube. I can't see why the flapper/overflow tube assembly would be the culprit, but that was going to be my next move and just replace it while I have the tank off. I know I could swap the one from the other toilet to see if that works but I don't want to take that tank off too. Does anyone have any suggestions? I can't find any other situation online that is the same. The only other thing I can think off is get the see snake back from work, and camera behind the rim around the flush holes to see if something is blocking. But I'd say that is unlikely. Again, its odd that once in a while the thing will just flush normally. It does exchange the water though, as yellow turns to clear for #1's. Can't be a factory defect either as it flushed normally for the first 2 years. FYI, I'm on an acreage with good city (Saskatoon, SK) water. I have a drip system with two tanks and a pressure system. Can't think of anything else for clues. Thanks in advance for any suggestions!