Any tips on unwinding? I imagine going from 3ohms to .8 is going to require a significant amount of removal.
Be warned, this is tricky business. A lot of things can go wrong, and if they do, the yoke is trashed. Take notes and/or pictures along the way and don't rush. Understand that this is a hack, and if you're a perfectionist, you will probably decide the final result doesn't look quite as good or converge quite as well as a yoke built by robots. But I think you may find the results of this operation good enough.
If you want to try it, here's what to do:
(1) Remove the plastic cover to expose the ends of the windings. You'll see that the ends of the vertical and horizontal coils are attached to metal posts. Since the vertical coils are on the outside of the yoke, it should be easy to visually follow the wires and see what posts those wires connect to. The horizontal coils connect to the OTHER set of posts. Make a note of how the horizontal deflection coils are connected to these posts, then clip the wires to disconnect the coils.
(2) We want to get the two horizontal saddle coils out of the yoke. To do this, you'll have to disassemble the yoke. (a) Remove the glue holding the vertical coils in place. (See first pic.) (b) Using a small flathead screwdriver, pry loose the clips that hold the two halves of the toroid together. (See second pic. Don't lose the clips!) Be careful from here on, since the heavy toroids will be hanging from the posts by a couple skinny wires. If the wires break, it's not a catastrophe, because you can reattach them, but it's easier if you don't break them in the first place. (c) Pry apart the two plastic halves of the "bell" of the yoke. This may require undoing, or even breaking, the plastic locking tabs on either side of the housing. With the horizontal saddle coils disconnected from the posts, they should fall out on their own, or you can wiggle them out manually.
(3) Each of your horizontal coils probably looks like the one in picture no. 3. You'll see that the windings are glued to each other to keep them conformed to the saddle shape. Grab the loose wire on the OUTSIDE of the coil and start unwinding by carefully, but firmly, peeling the wire away from the other wires. Do NOT force it -- pull too hard, and you'll break the wire, and you will have major problems trying to retrieve the broken end that's now buried within the coil.
(4) If the wire gets stuck, or you find yourself using too much force trying to peel it away from the winding, use a lighter to heat the area of the coil where the wire is stuck. Usually a little heat will soften the glue enough that the wire will then pull away without any problem. Don't let the flame set fire to the glue or the enamel coating on the wire.
(5) Sometimes you'll find that the wire takes a detour into the "inside" of the coil; that is, that instead of running along the outside edge of the coil, it dives underneath a bunch of other windings. This can be a problem, but using a lighter and a small, sharp tool like a dental pick, you should be able to gently pry the wire loose and continue unwinding.
(6) At this point you may be wondering how much wire you should unwind. Better to unwind too little than too much, because you can always unwind more, but you can't put back wire you've already peeled off. Also, the magnetic field generated by a coil is proportional to the number of windings in the coil, so if you take off too much wire, you may not have enough turns left in the coil to get full deflection even at max current. The resistance of the coil is proportional to the length of wire in the coil, so if you want to decrease the coil resistance by half, unwind half the wire. (In your case, I'll venture to guess you'll be OK at around 2 ohms resistance, so aim to remove about 1/3 of the original 3-ohm winding.)
(7) The amount you unwind is not critical; you only have to end up in the ballpark of your target resistance. What *is* critical is that you unwind the two saddle coils by the same amount. Any asymmetry between the two coils will mess up your convergence and distort the display since one coil will have more turns (and therefore more magnetic influence) than the other. I have two ideas about how to keep the coils symmetric: (a) To measure how much wire you've peeled off, wind the unwound portion around a spool -- or even your hand -- and count the number of turns. E.g., if you unwind a length of wire that loops around your hand 40 times, make sure you take 40 hand-loops of wire off of the other saddle coil. That's the way I did it, and it was good enough. (b) A better way would be to use a small electronic scale to weigh the coils as you unwind them. That way you can determine how much wire you've removed by how much lighter the remainder of the coil becomes.
(8) When you've removed enough wire, cut off the part you've unwound, making sure to leave enough length to reconnect the coil to the solder posts. Remount the saddle coils in the yoke housing. Although the coils are now noticeably smaller, they're still the same shape as the original coils, so they should fit back into the housing just fine.
(9) Snap the two halves of the yoke housing back together. If the locking tabs and slots are mangled, no worries; a little hot glue will stick those puppies together real good.
(10) Before you solder the ends of the coils back onto the posts, you have to remove the enamel coating from the coil wire. I like to burn off about a half-inch of coating using a lighter -- it will actually produce a small, brief flame. When the flame burns out, scrape away the sooty residue by running the end of the wire over a file, or an emery board, or, best of all, some 400-grit sandpaper. You will be rewarded with a shiny bit of uninsulated wire, ready for soldering.
(11) Re-solder the coil ends to the posts. You did take notes on which wires go to which posts, didn't you?
(12) Replace the vertical coils on the yoke housing and snap the metal retaining clips back into place.
(13) At this point the coils are electrically reconnected and the yoke is mechanically reassembled. You may notice the horizontal saddles and vertical toroids are a little jiggly since you removed the glue that was holding them in place. Don't worry about that yet.
(14) Place the yoke on the CRT and plug it into the monitor PCB. Don't bother with the purity rings at this point; we just want to verify that we have proper horizontal deflection.
(15) Put the neck board back on and fire up the monitor. If everything went well, you should now see full horizontal deflection. You can adjust the width by using a hex key to twist the core inside the width coil. (Note that if you turn the core with a metal tool while the monitor is turned on, the tool will get super-hot. This is definitely not recommended. If you don't have a plastic tool for adjusting the width coil, do your width-coil adjustments when the monitor is powered down.)
Finish up by hot-gluing the saddles and toroids in place, replacing the purity rings on the CRT neck, and adjusting the convergence.
Good luck. Let me know if it works.