Folding Seat Backrest Lever

I'm hoping someone here can help... I've had one of the backrest levers get dislodged somehow and I can't figure out the best course of action to refit it?

I've attached a few photographs so you can see what I mean. 

Has anyone encountered this before?  As you can see in the photos the red 'flag' which pops up when the seat is not latched in can no-longer come up through the hole because the whole fitting is dislodged. 

I'm not sure if brute force is the best option or going about disassembling the whole seat. 

Any advice is appreciated