Plumbing and Piping - Have to hold down handle to flush toilet

I've just moved to a new place, and found that the toilet will only flush if the handle is held down. I tried shortening the chain, but discovered that no matter how short the chain is, the flap (plug) will not stay up because it is installed flush against the overflow pipe (the rubber actually fits around the tube).

Any suggestions would be appreciated. I don't think my landlady will pay for a plumber since the toilet does still flush. Problem is, it's very hard on my bad back standing there holding the lever down.

Look in tank and see if the overflow tube has little "ears" at the base. Look at the flap for two rubber holes that will slip over those ears. If both are there, cut the piece out that fits over the overflow tube, install the flap on the ears and see if that doesn't solve your problem. If not, get a new flap. Good Luck.

Thanks, I'll have a look at it and see what I can do. If I don't have any ears, is there a particular type of flap I'll need?

Just a standard flap. Try Kohler.

I would change the flapper and the handle,the handle has reverse threads.