Zanussi oven door comes off

Hi The main oven door on my zanussi oven came off when I opened it. It fits back on , but will come off fairly easily. It looks like something may have come off the top hinge, there's a small metal pin that fits into a hole on the oven, this moves up and downModel no. ZCK68300Xserial no. 740 24808PNC. 948905054 .Thankyou