In 2003 I installed a new Raypak pool and spa heater. Fired it up and it worked. Turned off the power to the unit. Fast forward to July 2013 turned it back on for the first time and the water temp would not stabilize the display was jumping all over the place. Replaced the temp sensor with the same two wire model. The original one measured an open circuit when tested. Installed the new one and the temp is still bouncing all over the place. When the water temp indicates below the set temp the unit turns on and the low nox fan kicks in and everything works fine until the displayed water temp jumps above the set temp and it turns off. The control board PN is 601588. Looking at the board it looks like a 47u 20 volt cap is across temp sensor with this parallel RC circuit feeding probably an A to D convertor. Could this cap be bad. Board and heater look brand new as the heater has had a heater cover on it all this time and never been exposed to the weather here in southern California.

Thanks for the help in advance.