The item in pic #1 is the auto-shutoff valve. If it's shaking / vibrating and not turning off, there's likely either some air (most likely) or a dirt particle causing your problem. Tapping / shaking it should help clear any air, as well as tilting it more up and down while trying to clear the air (with the outflow from the valve facing up). For the auto-shutoff valve to work, it does require a manual shutoff valve on the end of tubing after the DI cartridge to create back pressure. Is the metal valve in pic #4 after the DI cartridge? If so, and it's not plastic lined on the inside, I would recommend changing it out for a plastic valve (readily available at places like Lowe's in the plumbing aisle). Running DI water through any kind of metal fitting or tubing kind of defeats the purpose of RO/DI purification, as the highly purified DI water can pull metal ions out of the metal fittings / tubing. The ions pulled from a single valve or fitting might not seem significant, but why spend all that money on a RO/DI unit and waste 4+ gallons of water for every 1 gallon of product water made to have purified water, only to be putting metals back into the water after it's filtered? Considering the toxicity of metals for marine invertebrates and the tendancy for metals to accumulate in a tank over time, the RO/DI water contacting any metal isn't the best idea over the long haul.
