A long time ago I ordered a new 37-key Doepfer keybed and cable from in the USA. In fact I think Doepfer gets them from in Europe so there might be a better way to obtain one. The new keybed is make/break (velocity sensitive) style, but the Pro One does not have the pinning to make use of the break contacts, so I only used the make ones.
Long story short, after making a new cable out of the supplied Doepfer/Fatar one and a 16-pin DIP, my Pro One keyboard is like brand new! The new keybed will fit in the Pro One, but the hole pattern on the bottom of the synth need to be drilled. This is fantastic news for anyone that has the membrane style Pro One keyboard. Anyway it will work with either the original Pro One CPU or my new TurboCPU. I have a couple of photos, but will also upload a wiring pinout later when I get time.