Hi Dyson,
First things first, the quality of your heads on V15 and Gen 5 are top class. However, particularly on thicker carpets that you see less of, the wheels fall off. Unlike other Dyson variants you cannot change the wheels. Dyson have been exceptional in dealing and replacing heads under warranty and just outside of but I still have bought an additional one for rainy days, which has a year warranty. But in short, while I understand you can't return to the days of turbo head wheels built like tanks from your cordless machines, can you not create a sturdier wheel, a replaceable wheel or a head dedicated to thicker carpets with a bigger design eg an outsize style head with better or replaceable wheels? The biggest issue I find with Dyson's is this and if availablity is limited, it can be bad news for the customer.