Symptoms
- The same few notes go flat soon after every tuning
- Unisons of a single note drift apart quickly
- The tuner mentions pins turning too easily
- Some notes drop out of tune after a hard playing session
Likely causes
Age and wear
The pinblock is a laminated hardwood block that grips each pin by friction. After decades of tuning and climate cycles, the holes slowly enlarge.
Dry air
Very dry conditions shrink the wood around the pins and reduce their grip. Repeated dry seasons make this worse.
Cracked pinblock
A crack running between pin holes makes several neighboring pins loose at once. This is more common in old pianos that lived through extreme climates.
Past repairs
Pins that were pulled and reinserted, or treated with liquids in the past, may not hold well.
What you can safely check yourself
- 1Write down which notes go flat and how soon after tuning.
- 2Measure room humidity; long periods below 40% can worsen loose pins.
- 3Keep the piano away from heaters, radiators and AC vents.
- 4Ask your tuner whether any pins felt loose during the last tuning.
What not to do
- Never turn or tap tuning pins yourself with pliers, a wrench or a hammer.
- Don't apply 'pin tightening' liquids or CA glue without a technician — once applied, it limits later repairs.
- Don't keep re-tuning slipping notes without having the pinblock assessed.
Quick fixes vs. call a pro
You can usually handle it
- Tracking which notes slip
- Keeping humidity steady around 40–50%
- Moving the piano away from heat sources
Call a technician
- Measuring pin torque across the keyboard
- Driving pins slightly deeper or fitting oversize pins
- Pinblock treatment when appropriate
- Pinblock replacement as part of a rebuild
What a technician will do
A technician feels the torque of each pin while tuning and maps the loose ones. A few loose pins can often be fixed in one visit by tapping them slightly deeper or replacing them with oversize pins. If the whole block is failing, the options are a pinblock treatment or a pinblock replacement, which is a workshop job lasting weeks and only worth it on a piano of good quality.
A piano holds about 18–20 tonnes of string tension. If a fix means opening the action, turning tuning pins or working near the strings, leave it to a technician.
In Israel
Pianos that spend years near AC vents or in heated Jerusalem apartments in winter are more prone to dried-out pinblocks. Steady humidity is the best prevention.