Thanks to folks who responded.  Here are the recommendations:

Gloria Horn Sewing Studio – Castle Shannon/Mt. Lebanon
www.gloriahornsewingstudios.com
 
Tim Grottenthaler
724-287-5075
Better with older machines (including antiques), Singers
He apparently does repairs for Joann Fabrics in the N. Hills (also recommended).
 
Thornton
http://www.thorntonco.com/home - N. Hills & Murrysville