When it comes to purchasing a used upright piano, I've been in your shoes before, and I'd be happy to share some insights from my own experience and what I've learned over the years.
First, when you inspect a piano, start by looking at the exterior. Check for any signs of damage or excessive wear on the woodwork. Water damage can be particularly problematic, as it may indicate warped wood or internal rusting. You'd be surprised how often moisture sneaks its way into these instruments, especially if they're stored in basements or garages.
Next, open the lid and take a look inside. The strings and hammers should be free of rust and corrosion. Play each key to ensure they produce sound; this will also help you test for any dead keys, which can indicate underlying mechanical issues. It’s important to also listen for unusual buzzing or rattling, which could suggest loose parts or structural problems.
A common issue with used uprights is that they often haven't been tuned in a while, which can give you a false impression of the piano's sound quality. While it's normal for an out-of-tune piano to have some pitch issues, too much variance might point to other problems with the piano’s pinblock, bridges, or soundboard.
Regarding professional evaluation, I can't stress enough the importance of having a qualified piano technician inspect the piano before you buy it. They can provide a detailed assessment of its condition, highlight any repairs it might need, and give you an accurate appraisal of its value. While there is a cost associated with this, it could save you from much larger expenses down the line.
As for where to find reliable options, I'd recommend checking with local music schools or piano teachers, as they often have networks of musicians upgrading their instruments. Alternatively, piano shops sometimes sell used models with a warranty, offering some additional peace of mind.
To sum up, patience and diligence are key. The used piano market is full of gems and pitfalls alike, so taking the time to thoroughly inspect any potential purchase is critical. What's your budget for this purchase, if you don’t mind me asking? I could suggest some models that offer great value for their price.