Are the jack springs weak or bad in my Wurlitzer 200?

Let me answer your question with another question, have they ever been changed before? Then, yes, they’re weak, and probably bad. In all seriousness, once installed, a jack spring (which is a pretty thin gauge) is constantly in use because it’s always under tension. Fast forward 50 years and you have a spring that is likely close to being worn out. Add rust or oxidation and they’re definitely worn out.

What are jack springs? And, What do jack springs do?

The jack spring is a small, thin gauged metal spring about 1” tall that sits between the whip and the fly on your 140 or 200 series Wurlitzer. These are also in upright and grand pianos and come in a few sizes depending on the model of your piano/keyboard.

Jack springs are what make the action in your keyboard pump, so in a way they are like the heart of your Wurlitzer’s action. They help move the hammer up, and help it return. A good jack spring is responsible for giving your keyboard speedy response and life.

Earlier Wurlitzer Models Without Jack Springs

Early Wurlitzer electronic pianos, such as the 112, the 112A, the 120 and the 700 don’t have jack springs in their design. You can instantly feel the difference. There are smaller, more simple springs in the dampers, and in the hammer butt which help the action move along, but these are not as powerful as a jack spring. The resulting feel of these earlier Wurlitzer electronic pianos is a little clunky.

A Tell Tale Sign of a Bad Spring

Unfortunately jack springs don’t always just fail. They weaken over time until they stop doing their job. Weak springs can be hard to notice and cause the hammer’s motion to be more sluggish. A weak jack spring will cause soft strikes to be even softer and often not strike at all.

However, an obviously spent jack spring will cause the hammer to let off prematurely. This becomes noticeable when regulating the let-off. In the case of a bad jack-spring the fly will never reach the let-off screw. The result here will be lower than desirable let-off regardless of how high the let-off regulating screw is set.

How to Install New Jack Springs

Our recommendation is to replace the entire set, but you can only replace a few if you are short on time. Our theory is that the metal springs wear out at roughly the same rate across the keyboard. So the springs that are “still good” might be on their way out soon. To replace the spring, the entire action assembly needs to be removed and disassembled. Applying heat to the old springs will loosen the glue, and a fine needle nose plier can grab the spring and pull it out. Some prefer to use acetone, which is a harsh chemical that can dissolve and loosen glue. The remainder of the glue can be cleaned out using a specialized jack spring hole reaming tool. Once the hole for the spring is cleaned out a new spring can be installed with a small dab of wood (or hide) glue from your hardware store. Let the glue dry for about 30 minutes and your are ready to re-install that whip assembly.

If you are interested in buying new jack springs for your Wurlitzer 140 series or 200 series keyboard check out our jack springs product page.