Seatpost worries - Help required

753 could be had in 27.0 and 27.2 seat tubes. And other sizes too.

If a 27.0 fits and is snug, use a 27.0. 753 can be paper thin in the middle, and doesn't take well to being forced.

If you posted a photo of the seat binder part perhaps it would help us work out whether it is deformed from being tightened around a too-small post or whether it could be prised open.

Cheers BlueQuinn, I'll post a pic tomorrow.

Thank you all for taking the trouble to reply.

Having seen the link kindly provided by provenrad, I'm now even more anxious to avoid any sort of 'foul-ups'.