david
your before the pump water filter protects the pump. After it leaves the pump the water can get scale from the coil,rust from the fittings,dirt from the quick disconnects,teflon tape,ect... in the line. Then that junk goes into the spinner,the spinner on a water jet is ceramic and can get scorn or chipped, same as a turbo nozzle.
To prevent this you should start your wash unit and the burner with nothing on the pressure line and let it run for about a min. When in transit scale and rust get jolted loose.
Then use a in-line water filter on your surface cleaner and your turbo tips. This will prolong the life of these tools and the filters are about $9.
They clog up and are easy to take apart to clean, but i suggest you buy a couple of them.
If you notice a slow down in the spinner then you need to change the filter.[or clean at the end of the day]
Equipment costs are high and i feel the filter's are very important. These will add about 1/3 more life to spinners.
Hope this helps