I have a 7 yr old Arctic spa that won't stay @ the temp set point i put it at..... I set the water temp @ 102f & a few days later it drops itself to 98f. Now i'm talking about the set point, not temp control. The temp follows whatever the set point is set to, it just keeps changing by itself, intermitently of course. Does this mean it's the control pad or the mainboard (Gecko)? Anyone have this issue before?