Nilfisk C125.3

I've been after a pressure washer for some. My dad had a Bosch that was hopeless - leaks water everywhere. I was going to buy a Karcher until I read the reviews here. Nilfisk - so far - so good. Easy to put together - good set of tools and works really well. It came with a normal head and a dirt-buster head (brilliant - can't see why you would need anything else?). It also came with a patio cleaner, which I haven't used yet. I specifically bought one with a metal pump head (I suppose others are plastic?) for durability. Most people seem have problems after storing them over winter - perhaps they need to be drained or something?