There are people who sell new pianos, who may have a biased opinion about Steinway rebuilt pianos.
So today were going to explore the truth about rebuilt Steinway pianos.
1) There are rebuilders, technicians, and non-Steinway dealers who will claim that Steinway pianos built during the “Golden Age” are the best Steinway pianos ever built. This is a myth that has been around since Steinway started building pianos.
Now when they say non-Steinway dealers, we assume they mean non-franchised dealer’s. There are many piano dealers who are not franchised by Steinway. Let’s talk about the “Golden Age”
During the 1920s, the United States was on the verge of a massive change. As more and more machines were being invented and used all around the country, people continued looking for ways to increase productivity. One of the most significant inventions to come out of that time was the assembly line. This process spread to many different industries, and it helped turn the United States into a major economic power. 
Henry Ford was the first to invent a moving assembly line. It had a major effect on the culture of manufacturing in America. The Ford Motor Company was a pioneer in all types of production efficiency. In the 30s they introduced time and motion studies (Frederick Taylor) to monitor the workforce and improve productivity. People doing work faster to produce more volume in the same time. By 1940, with war approaching many industries adopted the same production principles used by the Ford Motor Company. Time was now money. There was a divide in America. Production for the sake of lower prices, and quality produced by craftsman.
If we look at the piano is manufactured during the 20s and 30s, we see high level of detail, what we would term extreme craftsmanship by today’s standards. Time was not an important consideration in the manufacture of Art Case pianos. Some of the hand carved cases were even sent to Europe for carving. This added considerable time to the manufacturing process. But time was not a problem then. Quality, craftsmanship and sound was considered the most important factors. Over the years the Steinway Co has had many owners. There has been changes in the way pianos are manufactured.
2) “If it doesn’t have 12,116 genuine Steinway parts, it isn’t a Steinway.”
This seems to be a little bit over the top. If the screws and bolts don’t come from Steinway New York, does that mean it’s not a Steinway? Let’s stop and think about this. Is this a reasonable statement?
The majority of the controversy comes from the “action”. Some sales people will try to persuade you that, if it doesn’t have a “Steinway action” Or if it’s not rebuilt by the Steinway company, it somehow not a Steinway. The strong inference is that the parts are inferior.
What are Steinway actions? There are many top-quality piano rebuilders in America who rebuild Steinway pianos with Renner action. These parts are manufactured by Renner in Germany.
First, can you tell me any German manufactured product, that is inferior to American manufactured products? I can’t think of any.
Second, there are two production facilities for Steinway pianos. New York and Germany. German Steinway pianos are generally considered more valuable by American purchasers. They sell for a premium in America. The German Steinway pianos use the Renner action. It does not come from New York. So is it accurate to say, that a rebuilt Steinway piano, with a German Renner action, is somehow inferior to a Steinway New York action? You decide.
3) Fear and intimidation. Some piano salespeople use these techniques to scare the buyers away from rebuilt pianos. This is a common practice. Why would they not want you to buy a used, rebuilt Steinway piano? Could it be because the price is 50% or less of the new piano? Could this fact the so threatening, that they would not want people to know, that a rebuilt Steinway piano might actually be better than a new piano?
As Ed McMorrow, points out “The point I am trying to make is that manufacturers are not significantly moving the state of the art forward or most pianists would think that new pianos perform better than well rebuilt old ones.”  The fact is that many artists prefer the older piano’s.
When we rebuild a piano, time is not a major consideration for us. Quality is the most important consideration. We do not use cheap parts to make more money. We use the best available parts to rebuild the piano. That means Renner actions from Germany, not New York.