GPM Spas Chip Number 260/410E Part Number 51421
The 51421 is now obsolete. It has been replaced with 54003. If this board is ordered 54003 will be sent - Installs the same. It is important that you do not order a circuit board based on looks, several boards look alike but have different software or chips. It is the chip that drives the board and gives it its unique functions. To correctly identify a circuit board the chip number should be used to identify it. It can be found on a white sticker near the center of the circuit board. Another number that is helpful in identifying a Balboa Water Group circuit board is the five digit number found on most boards (5****).