The first thing to do when buying a ‘pre – loved’ piano (or if you are offered a free one), is to assess the casework-are there any signs of general damage, such as missing or splintered veneer, damaged castors/feet, corrosion on the hinges, pedals etc. indicating that the instrument has been damp at some point, perhaps left in a garage? More seriously, are there any signs of woodworm? and if so, is it active? Don’t touch the piano if it is!
If you can, remove the top & bottom doors (the panels that face you, above and below the keyboard), also the fall (keyboard cover). If you have any misgivings about going further than the outside of the case, then you should enlist the services of a qualified Piano Tuner/Technician, to help you in your search.
Have a look for broken or missing keys – these can’t always easily be replaced. Missing hammers will also need to be replaced. Another sure sign that the piano has been in a damp environment, is rusty strings. These do not always take kindly to being tuned, and many could break during tuning. Any signs of water damage on the case, keys or action, should be viewed with suspicion. A vase of flowers, mug of tea, or similar, could have been spilt inside, potentially causing hundreds of pounds worth of damage, or writing the instrument off completely.
Moth damage can be fairly catastrophic for a piano, with a lot of the main wooden components relying on a cushion or spacer/washer of felt, as well as keyboard and pedal trim. It is worth checking that the pedals are working correctly. If not, some further work may be necessary in order to rectify the problem.
A serious problem which would probably write off the piano, or make it terribly difficult to hold in tune, is cracks in the iron frame itself. Obviously, they only need to be hairline cracks, to compromise the string tension and any grip the tuning (wrest) pins may have. So if these can be spotted before purchase, along with small splits in the wrest plank, radiating out from the tuning pins, a lot of money and anguish may be saved.
If you would like any help or advice on any of the above issues, please do not hesitate to contact me. My advice is strictly impartial, and is my own professional opinion only.