The movement in piano actions becomes sluggish due to the centre pins corroding and binding on the cloth bushings in the flanges. In laymen's terms the action develops "arthritis" and becomes so stiff, the instrument becomes unplayable. In certain Rotorua areas, where sulphur is a product of the local geothermal activity, the reaction from the sulphur can greatly accelerate the seizing up process. If the jacks are affected, they will fail to return and the affected notes simply won't work. The hammers at best will be sluggish and will probably fail to return to the hammer rail, especially in the treble section. The wippens tend to be less affected, but even though they may still operate, they will be slow to drop. Removal of a bridal tape and the key underneath is likely to reveal this. The dampers are least affected, as the springs, if in good order, will override any stickiness except in the worst of cases.
The are no real options open to the customer, except to have the action completely recentered. Before even discussing the cost with him or her, I carefully decide if the work involved will be worth it. Also, I check the felts, leathers, tapes, springs etc. and sticking keys. If the overall condition and value of the piano does not make the repair worthwhile, I would look at other options such as installing a heater or placing the instrument in a warmer room. The problem will still be there, but it may mean the difference between having a piano that is playable and one that isn't. There is always the option of doing only the parts affected or just the hammers, but I strongly discourage this piecemeal approach to the repair.
In reality, I find that most recentering jobs are justifiable, even if they are not necessarily economical. It comes down to this: If the instrument is a reasonably good one, and the customer is reliant on it for his or her playing pleasure, then it should be done. Until it is repaired, the piano is little better than useless. While the value of the instrument may not increase as much as the cost of the repair, the customer can still be assured that the benefits will be gained in playing pleasure as the years go by. To sell the piano shortly after the repair in most cases would not be a wise move for the customer. It is important that a full discussion on all the above options be entered into prior to a decision being made. Should the customer decide to go ahead, I indicate that the overhaul takes about three weeks. The action is removed from the piano and is taken to the workshop for repair.
In the last twenty five years (2008) I have recentered over 200 piano actions, most of them requiring complete repinning throughout. That's a lot of centrepins - about 60 000!
Now go to part 2.