Remedies for stiff action

1. Silicon Spray
One of the most common complaints from people who have bought used Rhodes pianos is that the action of the keyboard is stiff or sluggish, even when the piano looks like it's in mint condition. One way to smooth out the action is to use silicon spray on the Key Pedestal Felts (see Figure 2-1, 27 or Chapter 8). Steve Woodyard explains where to apply the spray, and what kind to use:
The factory used Krylon Silicone spray 1325. Any hardware store that carries Krylon paint can order it. If another brand is used test it on the side of one of the hammers. Some sprays have solvents as propellants that can brake down (melt) the plastic. The silicone was sprayed on the red key pedestal felts (or white felt strip on the underside of the hammer).
Word of Caution: Krylon has stopped making the silicon spray used in the factory, so you must be careful if you choose a substitute spray. Note Steve Woodyard's suggestion about testing different sprays to make sure they don't melt the hammers.
Justin Pinnix recommends this substitute:
CRC brand "Heavy Duty" Silicone spray. I bought a can of this from Ace hardware for $2.50. It has the same propellant and warnings as the Krylon did. I put it on mine a month ago and it works great. Make sure whatever you buy doesn't have Acetone in it, and as always, spot test it first.
R. Barnum adds:
If you have a "Fender Rhodes" with the red felt on the end of the key when you pull a key out- this is where you spray it on your rhodes. If you have a later model thats just a "Rhodes" then you have to look on the underside of your plastic hammer where you should find a little piece of white felt- this is where you spray it on these models. The felts I guess harden up and thats what causes the stiff action-friction! The factory and other stores and stuff that shipped out rhodes- always sprayed a fresh coat of Krylon Silicone Spray on those spots. It has to be Krylon though or else its not as effective and it could eat through your plastic hammers if its corrosive, so make sure its Krylon. Your rhodes will be ten times easier to play if you do it right! Good luck everybody! R. Barnum This treatment will make the action much lighter. Afterward, you may need to change your playing style slightly, in order to avoid overstriking the tines.
 
2. Teflon Powder
Tim Nelson offers an alternative solution: Teflon powder!
I'd like to put in a plug (again) for the suggestion made by my piano tech for restoring/improving the action for my Rhodes Mark I: dust Teflon powder onto felt bearings of the action (instead of using the Krylon silicone spray), using a small brush. This is the treatment used on acoustic pianos by many techs. Teflon powder is available for this purpose from piano supply sources, but probably not at the local hardware store. The powder becomes embedded in the felts, making them silky smooth. It is more time-consuming and more expensive than using the silicone spray, but if you're crazy about your Rhodes like me....
 
More detailed information on the Rhodes Action can be found in the Rhodes manual:
· Chapter 2: The RHODES Modular Action;
· Chapter 8: Early Design RHODES Pianos - Action (Prior to September 1975).