My philosophy is…if it can’t be fixed with a hammer…
Get a bigger hammer.
The curious thing is, why does the problem not instantly reappear as soon as the violence stops? Often the “cure” will last a fair while. As others have pointed out, the problem is the connectors, invariably the weakest point in many electronic systems, and they don’t get better as they get older. Now connectors (and switches and relay contacts etc) have a maximum current rating, which when exceeded will burn, melt or arc-weld the contacts. Less well known is that there is also a minimum current rating, below which the electrical connection can’t be guaranteed. Generally, the higher the maximum current rating, the higher the minimum current rating too.
This minimum current rating is due to metal oxides, salts and sulphides, as well as thin layers of oil and general insulating dirt. This insulating crud can be punched through by a little voltage, and if this is followed up by the required minimum current the array of tiny sparks thus produced keep the insulating layer burned away. Bashing an electronic gizmo with an unreliable connection momentarily jiggles the contact mating faces such that the insulating layer is compromised, gets punched through by the applied voltage, and the connection maintained by the current. Switching the device off and leaving it for a bit may allow the oxides etc to reform, and the cycle of violence is satisfyingly repeated.
My first ever full-time job (some 20 years ago now) was as a TV repair technician in a Toshiba TV factory. Part of the production test involved someone hitting the top of the set with a big rubber hammer while it was powered up, and any that flickered or died were rejected to be repaired. We weren’t issued with hammers, so I developed a technique of kicking the underside of the trolley the TV was sat on - very therapeutic, and it didn’t mark the set. One time I performed this scientific manoeuver, making the TV jump a couple of inches in the air, only to turn round and see the horrified faces of a group of senior Japanese management who had come down for a visit. Bonus!
Anyhoo, the way around the dodgy connector problem is to use gold-flashed mating surfaces to resist the corrosion (expensive and still not totally guaranteed, plus gold plating is not good with high currents), or to use sealed relays and switches in a noble gas atmosphere (again, not good for high currents), or best of all, forgo the connector altogether and go for a well-crafted lead/tin solder joint, just like in the old days before labour got really expensive. I had an old '85 Mercedes for a little while, and the wiring loom was mostly solder-terminated. Very reliable. I’ve also got a weakness for big Citroens, which alas seem to be 20% shitty connectors by weight, and due to these I’ve had intermittent problems with airbags, headlights, climate control, tail lights, washer fluid low warning, fuel gauge, suspension control, and so on. Currently I’m occasionally being told that the radiator is about to boil over, which I’m ignoring as I know the engine is stone-cold, so I start it up in great clouds of white smoke (the fault throws the ECU), and then after a few seconds it self-clears and doesn’t go wrong again for another day or two.
If you can isolate the offending connector by judicious jiggling, a squirt of proprietary switch cleaner aerosol and a few mating/unmating cycles will invariably cure the problem for a fair while.
Mine too. There’s magnetic metal disc that drops down onto the centre of the DVD disc and clamps it to the motor platter. On my LiteOn piece of junk this magnet is now stronger than the mechanism that lifts the clamp on and off (either a weakening motor or a slipping clutch or belt, I can’t be arsed to investigate further), and a sharp smack above the loader mech at the crucial moment is sufficient to encourage release/engagement.