Mine is exactly the same and I have thought about having a go with brown silicone filler (the type that comes in trigger tubes), but this is difficult to rub down once set. For the moment I have decided to leave it. At the end of the day the dash material has been hardened by the sun and was probably too hard in the first place - modern dash material tends to be either slightly rubbery (in quality cars) or very hard (and plasticy in cheap cars). The dashes probably creaked like mad until they cracked.