In the mid-80s there was a spate of Sea King HAS Mk5 radar control set failures. (RAF - you had something similar, the box at head height with lots of black knobs). It transpired that someone with good intentions had put masking tape along the inner seams to stop oil, which dripped (poured) down from the MGB drip tray onto the LRU, then leaking out through ventilation grills onto the consoles/PPI display. Ventilation/cooling is usually quite important in avionics. CRSs were being removed with an inch of oil in them, cooked to perfection.