Paulie, the old adage applies: If It Aint Broke, Dont Fix It. *Depending on where you live, the most likely foreign bodies will be lime scale calcium/magnesium deposits from hard water.
These collect in the boiler, especially over the heating element. *Over time, if not treated, the element sill be so insulated it many not heat. *And the flow of water will be reduced.
If you have an electric jug, take a look at the element. Is it covered with a rust-like deposit? If so, you need to descale your coffee machine (and jug) with citric acid every few months.
Other deposits: look at the two silicone hoses from the water tank. Do they look clear and clean? Is the bottom of the water tank likewise?
Metal deposits come from rusted galvanised pipes common in older *houses. *Some cheaper machines use aluminium boilers and are prone to electrolytic corrosion.
The best way to eliminate both metal and lime scale is to use filtered water. *We use a filter jug and replace the filter element at the recommened intervals of 150 litres. Thats about 3 months worth for about $8.
But again, apart from removing the shower screen regularly for clearning, keep those tools away from the machine. *Youll be taking things apart for no reason, risk damaging them (and electrocuting yourself) and will need all sorts of gaskets before reassembly.
Hope this helps,