When buying a second hand piano there are 3 main factors to consider?
1. Has the piano got an 'iron frame'?
2. Is the piano 'over-strung'?
3. Has the piano got an 'underdamper' action?
1.Wooden frame pianos are now obselete and cannot be tuned to concert pitch. When inspecting a piano to determine whether it has an iron frame, lift the top lid and look down into the piano. If you see any iron framing around the tuning pins, the piano most likely has an iron frame.
2. With the top lid of the piano still open, have a look at the way the piano has been strung. If the larger double wound bass strings travel from left to right crossing over in front of the treble strings, the piano is overstrung. If the larger double wound bass strings travel straight down in the same angle as the treble strings the piano is most likely 'Straight Strung'.
3. With the top lid of the piano still open, have a look straight down into the piano action. If you see 88 white hammers (Approximately 2 inches in length) that travel towards the strings when the keys are depressed the piano has an 'underdamper' action. If you see a long wooden board approximately 3 inches wide and running the length of the piano, the piano most likely has an older style 'overdamper' action.
Aside from these three important factors, there are other more minor factors that are to be considered such as cracks in the soundboard and tuning plank. If you are at all unsure, contact Mobile Piano Service for a valuation / assessment of the piano.