Is the Frizzen hard?
Sometimes these repo's come with frizzens case hardened. Once they are fired a few times you wear through the thin hardened surface. There must be enough carbon in the steel to reharden it just by heating and quenching.
It can easily be restored with Casenet compound available from Dixie Gun Works. Heat it to a red color, dip in Casenet, reheat and hold at the red color for several minutes, repeat to get a deeper case hardening. Hope this helps.
Regards, Dave