I'm having the same problem. Were you ever able to solve the problem, George? BTW, I've had other problems with the more recent versions of Finale in the past several years and the go-to "fix" the ...
I did find them: not only are they in the Engraver "extras", they are in the "percussion" part of the extras. I did peruse the extras last night, but must not have gone deeply enough in the percuss...