vertcal blind repairs

[woofgang]

Hi, My dear doggies have done their best to trash our vertical blind. I have managed to wash off the footprints and replace the weights and chains, however one of the semicircular cogged bits that sits on/in the header track and had the actual blind clipped onto it has popped out of its bracket. The cog thing and the bracket appear undamaged but i can't seem to get it to pop back in again although it looks as if it should. I have a feeling that there is a knack to it...can anyone tell me how/point me to a website so I can fix it please.
Thanks