From what I understand, the workers in the Rhodes factory were not trained piano techs, and tolerances were sloppy at times. A lot of times you will find the paper shims on top of the felt punchings on the balance rail. I was told they did this to save time, but to me that's just lazy.
There were several types ( felt, rubber, Square, angled) and shapes of hammer tips, but I'm not an expert on the different types. The tips are different hardnesses throughout the keyboard- softer in the bass and harder (sometimes rubber wrapped wood) in the treble.