Electrolytic capacitors represent the primary source of electronic circuit damage from failing components. Over time, almost all electrolytic capacitors fail, and that can manifest itself in a loud smoky pop with the capacitor literally bursting when powered up. Or the plague may be silent as they leak their electrolytes all over a PC board, damaging circuitry (or making shorts across traces) without making a peep. A sure sign of a failing capacitor is a canister bugled out top, as seen in the photo. Another sign is a tiny dried puddle of clear fluid sitting at its base on the circuit board. If you have a prized electronic device over 20 years old and you want to use it again some day, consider preemptively removing its capacitors—or replacing them with fresh ones as soon as you can—before they leak and irreversibly damage surrounding circuitry.

Don't mess around with lithium batteries!