I have noticed that there is some grease dripping out from the duct
connected to my oven onto the basement floor where subceiling has not
been installed. The grease is leaking in a section of the duct where
it is joined in a vertical section but the joint is constructed so
that the lower piece of duct pipe fits inside the upper duct piece.
The joint is riveted shut. The joint had been duct taped by the
builder and the grease is dripping through. Any ideas about a good
fix to this problem?

Thanks

Glenn