DG6145 tablet door not opening?

My Indesit DG6145 is misbehaving.

It began making a sound like a broken wind up toy a few weeks ago, which seems to be the timer. This passed and now it is working fine, except that the flap on the tablet / powder tray is not opening.

If I manually flick the release catch then it opens fine, but if I attempt to make a wash then it fails.

Any ideas?