Sounds like the corrogated flue vent pipe cracked. Very brittle,it is.Maybe
done when adjusting the flue when reconnecting the vent cover.Dosent take
much. Remove all the vent cover pieces.Put a cork in one ofthetwo
vents.Blow intothe other. Got a good seal?? If not,you may have a cracked
pipe. Muffler mend puddy will fix it up,I am, told. Also, check the little
drain in the interior at the floor.You may be able to find the leak in the
cracked pipe with soap bubbles.The kind used for checking for gas leaks.
Remove the side access and vent plate on the side of the interior cabinet.
Put this bubbles on the pipe ,through the assess. Saves a bundle of
time.May even be able to mend the pipe through the access.