I have a 2002 Hot Springs grandee that won't heat. I cleaned it and bought new filters. There are bubbles still coming out of the center so I assume the ozone generator still works. That leaves the heating element. It is a Watkins no fault 6000. I bought a new one online but it only has two tubes on it. The original looks like it has four tubes and is encased in plastic. All of the connections- water tubes, electrical, ground wire- are the same as the original. Can I use one of the new heaters even though it only has two tubes?