Nest too far down for fleglings?

Help!  We have a Great Tit nested in the pump of an old well.  The 'babies' are almost ready to go but will they get up the inside of the old cast iron pump????? - they are at least 12" down.  Can we do anything? 

Thanks for the replies.  They hatched about 14 days ago, so should start to emerge in the next 4 days or so.  The parents are still feeding but I don't think, quite so often.  I have had a quick look and I think there are 5, but it is so dark down there, it's possible there is a 6th lurking in the gloom but I didn't want to hang about too long.  Will keep you posted and fingers crossed!

10 June - good news.  Intrepid 'baby' no 1 left the nest about 5 mins. ago which I was lucky to witness.  He bumped into a brick wall (not surprising really as he has never seen one before), rested for a minute or two on the roof and has now flown up into a tree.  The other 4? have decided they prefer being waited on and seem to be staying put for the moment.  At least it answers the question of whether they could get out or not!

11June.  The old water pump was eerily quiet at 7am this morning!  A quick look confirmed that all the fledglings had gone.  All that worry for nothing - I shall  know better in future!