Looks like the transistors blew on the old board if they are getting that hot on the new board best to find out why the motor is pulling so many amps. Might check the the rest of the drive line to make sure nothing is binding.
if the transistors do blow you can replace them. I think they are TIP31 and 32. They are rated at 3A. I typically use 6A transistors when I replace them, the E units at our club get used a lot and tend to eventually breakdown.
