Thanks again for all your help and advice guys I received the parts from AGS this morning and have now renewed the transfer port seal and O-ring as well as the bolt O-ring and powerlet seal.
The transfer port ring and seal was a little fiddly to fit but it's all lubricated and reassembled now! Just have to remount the scope nice and square and then it's off down the garden to zero in.

Beardy

Crosman 2260 ( but wanting an Air Arms someday)