John,
Board looks good, only thing I saw was the possible bridge on the back of the board, just above the PIC, most likely it's an illusion. Also, on the front left, the H11AA1 Optocoupler is hardwired instead of in a socket, mine all had sockets for that, don't think it makes a difference, just thought I'd mention it. Just below the DMX Out are 3 small holes without parts, one of them looks filled with solder, which may be bleeding over into the next hole. Hope you find the problem and get it fixed, it's too close to blinky to be fixing stuff. Good luck,
Bill