Complex sentence: Though it is advised to allow a small flow, to wash away any loose shards of glass that may be adhering to the neck of the bottle, the first glass of Champagne poured from the bottle should also be checked for small glass shards.
Split into simpler sentences: Though it is advised to allow a small flow, to wash away any loose shards of glass that may be adhering to the neck of the bottle. The first glass of Champagne poured from the bottle should also be checked for small glass shards.