Hi, possible things to try:

Rouse it (agitate somehow).

If it's stuck in may be down on minor components such as a vitamin or mineral. So add some yeast nutrition?

Gary

Hi Gemma,

due to the closed system you have in Champagne production there are not many options:

- raise the temperature (remedies might be that then fermentation goes too fast; temperature impact on product)

- improve contact of yeast with product = shake the bottles (cautiously!)