The problem with Miele vacs is that the internal parts for them are either not available, or if they are, they are so expensive (like £160 for a motor) that it works out cheaper to buy a new vac.
Whilst you can get replacement hoses and tools, once the motor goes, its sadly beyond economic repair, and only really any good for spares, unless you can get another S4 with a good motor but knackered other parts.
I cannot understand that whilst you can get a new Dyson motor pattern part for around £20, you wont find a pattern motor for a modern Miele vac.