Hi Sean,
Stieff pianos were built in my hometown back in Baltimore , Md.
Downtown Howard Street I believe was there exact location.
I would say that at the time they were among the top 5 piano manufacturers. Steinway pianos were more popular but not better built.
The broken Action piece and key are fixable for under $100, the greater concern would be the age of the instrument and whether or not it can actually hold a tune. Since the pinblock is older it may not be able to hold the strings at proper tension. Hard to say without seeing the piano.
Hope this helps.
Sincerely,
Steven Malicki
www.orlandopianotuning.com
