Oh
shit. In your haste to remove
component X to get to
part Y,
you let the screwdriver slip and now you've stripped the head from the
screw. Damnit. So how in the hell do you get that bastard out? It's not as difficult as it sounds. Relax and have a beer.
One way to get the stripped screw out is to insert the appropriate screwdriver into the head and give it a few strong taps with a hammer. This may deform the head enough to give you a suitable engagement between the screwdriver and screw head to remove it. You might also try a screwdriver tip in an electric drill. While pushing the bit into the screw head as hard as you can, s l o w l y apply torque. If you're lucky, the screw will slowly back out of the hole. If not, read on
If the screw is holding on an access panel or (completely hypothetically, i swear!) the top to the brake fluid reservior on a 1982 Suzuki GS550L motorcyle, you can also try drilling out the screw head. This method is cheap and very effective but requires a steady hand and more concentration than the orange juice aisle. Either an electric or hand drill may be used. The hand drill will give you greater control but sacrifices speed. If you use an electric drill, go slowly. Take your time and pay attention to the screw head. Start out with a small bit and drill down through the center of the screw about a quarter of an inch (roughly half a centimeter). Drill down through this same hole with progressively larger bits until you have drilled through the head of the screw. Remove the access panel or brake fluid reservior top and take a pair of vise grips or locking pliers and remove the screw stub.
Not feeling as if you have the nerves of steel or steady hands required for drilling out the screw? Fear not, for the screw extractor was designed just for you. A screw extractor looks like a very coarsely threaded screw, only with left-handed threads (or a left-handed tap for those in the know). This means when you turn it counterclockwise, it tightens instead of loosening. To put this insidious piece of equipment to use, drill a small pilot hole into the screw head and insert the screw extractor. Trust in me like Kaa the Snake and turn it counterclockwise. The screw extractor will drive into the pilot hole, bite into the exposed screw material and back it out. Counterintuitive minus zero no limit.
A much more complicated method is to TIG weld a bar of a similar metal to the screw head. In effect, you've welded a wrench to the screw. Twist away with reckless abandon and delight in your freshly removed screw. This not only requires a steady hand and steely nerves but a three thousand dollar welding rig and all appropriate protective gear. This is strictly for showing off, but you certainly earn your Badass Welding merit badge by doing so.
Once you've removed the offending screw, throw it away and use a new one in its place. You may also want to chase the threads with a tap to ensure they are free of rust. Apply a dab of anti-sieze compound if you're so inclined.
and yes, i got the brake fluid reservior screws out, replaced them, then flushed and bled the brake line on my motorcycle.