Hello folks, electrolytic capacitors have they names because of its liguid in it, the electrolyte. In German we call them Elko (Elektrolyt-Kodensator). Elkos do have a minus pole and a plus pole. For that its is VERY important to solder them with the right side. The minus pole on an Elko is marked. The older Elkos get the higher is the probability that the electrolyte drains and the Elko loses more and more its capacitance.   For me that was reason enough to change the E