The simplest fix is to use pipe mud -
Cigar ash + water
Do not use pipe ash which may contain large bits of unburnt tobacco
Add the water drop by drop to the cigar ash
It takes very few drops to give you a workable consistency.
If it is too thick or too thin, it won’t stick to the chamber walls well.
Apply with a folded over pipe cleaner
Allow to dry at least 2 days
Then apply another layer of pipe mud
I usually use 2-3 layers
There are more complicated pipe mud mixtures.
Some will advise using water glass
But the above method is the simplest and has worked very well for me