We bought our house three years ago and everything flowed and flushed just fine. Over the past year, the upstairs toilet has been "on-and-off" in terms of flushing. It has never overflowed, but it just doesn't fully go down approx. 50% of the time. Sometimes it seems as if only an hour or so of waiting helps. I've tried a snake, but this white porcelain beast doesn't seem to like snakes, no blockages that I can detect. The basement toilet flushes just fine and no other upstairs water disposal problems exist.
Answer:
Try replacing the wax ring under it. It appears to have moved some and that made the old ring squeeze inward to block drainage.
