I heard it was a CPU swap, but either way the same method should work.
The Pro-96 was my baby with the help of a few other very talented people. We made a xls list of 200 complaints against the Pro-93/95 and tried to fix as many as possible while adding the digital capability. Still have the prototype in a shelf.
It was a OTP CPU so they decided on a board swap program because the desoldering would not make sense. That said I carted around soldering equipment and a 3D magnifier and halogen light with other RF equipment to hotel rooms when developing, probably replaced 20 CPUs. I pressed for the flash CPU, based in the success of my flash based DSP design for a good year before they approved that project.
Those were some fun days I'll never forget. Was neat hearing some of the first 9,600 baud control channels when no other scanner did it.
Kind of like being the first to release Moto phase2 even when GRE was already in the process of closing their doors. We did it in two months.