Tone Bar Springs

[trengag]

Do tone bar springs ever need to be replaced?
And if so, how can one tell which ones need replacement?

[The Real MC]

Only when they're rusted.

Rust impacts the spring properties.  It also acts as an insulator - the spring doubles as a conductor to provide a low impedance ground to the tone bars to minimize noise.  See that metal strip running the length of the harp right under the springs?  That's connected to ground.

[Student Rhodes]

Trengag,
There has been some discussion about the various springs as found on a tone bar.  Fender apparently used different grades of springs for different resistance, as sometimes indicated by different colors. 

Aside from rust, which affects ground continuity, I would imagine these springs may be subject so some level of fatigue, but I'm not sure that's a real issue for these pianos. 

However, I have seen some Rhodes pianos with double springs on some of the tone bars, I presume to give added resistance where needed. 

Ray

[David Aubke]

However, I have seen some Rhodes pianos with double springs on some of the tone bars, I presume to give added resistance where needed.

Here's a discussion related to doubling tone bar springs.