It is very common for Wurlitzer keyboards to have moisture damage under the keybed, whether from spills or humidity. If moisture-damaged, the paper shims will no longer work (or smell) the way they should. Replacing them improves playability.
Restoration tip: To refresh your entire keybed, replace the balance and front rail paper shims and felts as well. If your keys have excessive side-to-side motion, consider replacing the key bushing felt. Before re-assembling your Wurlitzer, use a metal polish such as Flitz on all key posts to remove any surface corrosion that might create unwanted friction when the keys are depressed. Finish with a drop of silicone on each keypost right before replacing each key.