Even the most rigorous of cleaning and sterilisation routines cannot get those hard-to-reach areas of the breastshield fully clean. Over time, fatty residue and condensation will build up in these crevices, making it a great place for bacteria and mould to live (this is why we recommend replacing breastshields every 6 months).
Always get new valves. This part needs to be replaced most frequently as the silicone loses elasticity over time with each sucking cycle of the pump, and there's no way of telling just by looking at a valve how long it has been used. There are two type of valves on the market - duckbill valves, and valve + membrane sets. Spectra sells both styles which are interchangeable on Spectra breastshields. Generally pumping mamas will have a preference of one over the other. Many mums prefer the duckbill valves because they are one piece and last a little bit longer. Some mums prefer the valve + membrane sets because the inside of the valves are easier to clean. Remember that both styles will need to be replaced regularly.