Fixing toilet push button flushing mechanism

[Daedroth]

This may be a very random question, especially for a tech-orientated forum, but here goes!

 

I recently bought my first house and it's all been fine and dandy. However, one irritation is that the push button on the toilet will often get stuck down. I know how to temporarily fix it, but it keeps happening and it's driving me insane! I don't know much about plumbing, hence this post!

 

The way it is meant to work is that the push button mechanism pushes down on a lever within the back of the toilet.

However, that mechanism is effectively dropping over and falling under the lever, meaning that it's got nothing to push against and gets stuck down.

The attached image shows an example mechanism that works the same way as mine, and with the same issue. The gray plastic bit is directly attached to the underneath of the button. It is meant to hook into the white plastic hook and push that down when the button is pressed, which in turn raises the valve to flush the toilet.

 

I can manually re-attach the gray clip into the white hook, but one or two flushes later, it's back off.

 

Anyone have any ideas?