OK, I have had issues with this toilet for the past week. I have called maintenance three times (I rent an apartment). The first time, I assumed it clogged and plunged it several times. The water will fill the bowl and act like it will flush, but would just swirl and go back to normal water level. The water would be clean after the 1st plunge. The flapper has been replaced 3 times. The third time maintenance came out, it was snaked 2 times, flushed fine, but real weak. Then while they were here, I had flushed it again, and it acted the same way, just swirled and didn't flush. So they proceeded to snake it again. Seemed to work fine and the flush was a little stronger. So tried it today and it flushed the waste perfectly fine (still kind of slow). So I decided to flush it again about 45 minutes later to make sure it would properly flush and everything was OK. It still stalled and didn't flush. I have plunged it again and still nothing. I'm perplexed and frustrated. I shouldn't have to call maintenance every time I use it. Clogs are one thing, but this is beyond me. I have not flushed anything unusual. I don't know what else to do.

There are may possible causes for this problem. One that is frequently over looked is that the water jacket(inner lining) of the tiolet bowl is cracked allowing air to interfer with the siphon action of the toilet. Solution: replace the toilet bowl.

Good news and bad news, keep calling maintenance since its not your problem if you are a renter. Bad news is that maintenance workers are not plumbers and each one may have not performed an operation correctly. thomasj suggests a cracked bowl , while not impossible, very very rare. Is there a 1" round hole down in the bottom of the sump area? Clear this out with your finger, this jet starts the siphon. As the small holes under and around the rim do clog with calcium and debris and need to be cleaned with a stiff brush. Give them one more chance and then skip maintenance and call management demanding a real plumber oand/or a new toilet.