I just bought the M4 last weekend and it did a wonderful job of cleaning the deep end, but I realized that it never came to the shallow end. I let it run for hours yesterday and the shallow end was still as dirty as when I left it. I start it in the shallow end, it spends about 10 seconds there then heads straight for the deep end and never comes back. Everytime it started coming back up, it veers off to the side and climbs the wall. I can't imagine why this would be, does anyone else have this issue? I've put the handles at different spots and pushed the turning dics out, basically trying all configurations.