Not sure if you saw it, but if can you get pics/part numbers (for triac, transistor) requested in the previous post it might be helpful in diagnosing the problem.
About the only thing that’s not easily replaceable is the Sonix microcontroller, as you’d need the code for that. Even then, an ambitious person could write equivalent code for the same micro and burn a new one. However, an easier solution would be adapt a more common micro, such as the Atmel processor that’s used in the Arduino boards. Then you have the benefit of all of the Arduino libraries and, most likely, a more capable processor than the original.