My first electric piano was the Wurlitzer 200A. I would tune it by scraping with a file lightly, similar to the melodica. When the reed would go flat constantly you would replace them. In the 10 years that I had 200A the reeds never went sharp they only went flat. The only reason you would have to flux and “Solder” lead to them was when you over filed, most of the time you would hit the note a little hard for a bit and it would compensate. I Also had a Fender Rhodes 73 suite case model as well. You would tune this by sliding a spring on a rod back and forth. Much simpler and cleaner system.