Truma heater falling apart

IanH

We've gotten used to the heater front falling off every trip. In fact these days, we have a bungee cord stretched across it to hold the front on during trips, to prevent it flying across the caravan.

However, on our latest outing, not only did the front come loose, but the top panel has now come adrift at one end!

I cannot see how this attaches - does anyone know how to re-attach this?