My 380 is acting funny, (I think he's getting old) he's acting like he's low on power. He does not climb the wall and turn like he used to. I checked the RPM, it was 12. I know it should be 28-32. I put the blue disk in the side of the pool. It had the red one. Now I'm getting 14 RPM. It does seem to be working better. At 14 he does get around the pool at a good pace. I changed the back-up motor, it was worn out. It is working, but not as it did last summer.. Question: Does the RPM have to be 28-32?