One of the two incandescent lamps in refrigerator flickering. Tap it (sign of loose/broken filament) yields no change in behavior (i.e., doesn't alter its state). Unscrew bulb, reseat -- no change. Inspect socket -- no issues. Inspect bulb base (solder imperfections, signs of arcing, etc.) -- nope.
Crap! Disassembling refrigerator to expose wiring (faulty contact?) risks breaking one of umpteen gazillion bits of plastic -- no doubt "unavailable" as spare parts.
Laziness prevails: swap bulb with counterpart and see if problem
*moves* (with the bulb) or stays in place (with the socket).In its new home, bulb flickers a little -- then gives up the ghost. Yay! Just buy a new bulb (leave the other one in its swapped location).