Help! What's the white glue coming from Celestion SL600SI

Hi,

Help! Can anyone help me make sense of the white gluey thing coming from Celestion SL600Si? I purchased them used from a seller here, have enjoyed them for 2 years, and noticed this anomaly today. Not sure when it started to happen. It looks like melted glue. See the pictures below:

https://photos.app.goo.gl/pTRLCsmanTfpMJCv1

https://photos.app.goo.gl/e55Mi2SmZTksccb22

https://photos.app.goo.gl/e55Mi2SmZTksccb22

Thank you!
Shoubang