[Wannabe]

Yes, the pads on mine slide off sometimes when not in use, but it's easy enough to fit them back on before use. When the cups are on your chest under pressure they stay in place well because of the suction, of course, so it's not a big problem. I suppose you could put some silicon caulk or an adhesive in the trench to keep it in place, but I don't think I will. I like to take everything apart and clean it well now just to keep it all sanitary.