Thanks for all the responses! With the insight gained from Researchers post I was able to get it apart and discover that the previous Smith had not gotten the vertical leg of the top lever aligned with its machined hole in the trigger plate. The result was a top lever higher than the top of the receiver, and the top lever would not return to center when released. Once I was able to get it properly aligned, it worked like a champ.

Truly appreciate everyones help!

John