MTH PS1 Bottom Board Keeps Blowing

This resistor on two of my MTH PS1 boards keeps blowing.  One is from a Class A and the other from an AC-6.  I am having trouble with the Class A (which prior had blown the pictured resistor), so I swapped in the working bottom board from the AC-6 to troubleshoot.  After the swap, the Class A seemed to operate properly as far as movement, but the sound was almost constant loud humming.  When I switched the bottom board back to the AC-6, that one also started loudly humming from the speakers and blew the resistor, just like the Class A had originally done.  Why does this resistor keep blowing?  Also, the components in the second picture look a little cooked, but it could just be sloppy soldering.   Any advice would really help, thanks!