The head does strip down, but its not straightforward. Nobody makes that square hose. We considered making it once, but as fitting it is not an amateur job it would have caused more trouble than it was worth with returns, etc.
Buying the correct head is the answer. IIRC the colours are all obsolete and all silver ones are all that's available. But these will fizzle out as Dyson support for that model has finished. Which means when the parts are gone, they're gone.