"Give it time"
The lip round my sink was higher than allowed for by the design, meaning it sloped away from the sink. I decided to resolve the problem myself, by lying it on top of a thick absorbent cloth. It worked but the cloth gradually became wet, and needed regular changing. So I let the excess water sit in the channels, tipping it off as necessary but, when they dried inevitably there were small 'bits' that had dried hard on the inside edges (very fiddly to clean off). I realised that after finishing with it - I just need to stand it up on end in the sink and let it dry that way. It works.