Kimkats, the M400-500 are a different series and very different design from the "So this just happened..." post. I run my M500 (same as M400 but with mostly useless Bluetooth app support). I run it once a week, sometimes twice, but I always take it out after a 3.5 hour run time. I then clean out the filters and rinse off both all the cleaner and cable, making special effort to flush out all the places that might retain chlorine. I especially rinse out the path of the vacuum propeller. Watching it at work, it seems the keys to wall and waterline cleaning are the vacuum strength and the floats, which I keep at a maximum angle to facilitate moving along the waterline. After rinsing, I let the cleaner dry on its caddy, then cover it to protect from the sun. This cleaner with its third brush placed amidships, does an extraordinary job of scrubbing the pool bottom and sides (especially compared to the pressure side cleaner the PB provided!) When asked, I usually recommend the M400, as I have a program set (3.5 hours, bottom and sides) and have neither the desire nor the need to manually drive the cleaner around the pool.
All that said, after two seasons, it does seem to not climb quite as high on the waterline as it did the first time I put it into the pool. My pool has a kind of pebble finish, and I suspect that increases wear on both the brushes and tracks, although that wear is not obvious to look at. I wonder if a soap and water wash of those moving parts would be beneficial. Could the tracks plus front and rear brushes have accumulated oil that is not obvious to the touch or eye? I use the pleated filters pretty much all the time, as they should have greater filter area than the others, but I'm not certain about water flow resistance. Elway, keep us posted on your efforts and results, please.
