Two options .
# 1 completely disassemble and remove tin bottom and replace with a brass one . Soft solder will be sufficient.
# 2 remove most of the tin bottom leaving about 5 mm all around as a ledge and soft solder a new brass disc .
Silver solder requires higher temps and likely to cause you more issues .
No way i hell would i use epoxy. In my opinion there is no use in engineering for glues or epoxy
Cheers
Dennis