The first order of business in igniter repair is never be afraid to try your luck, and if all else fails, you can send it to any of several professional repair businesses advertising in GEM.
The basic procedure in repair is to first determine if the moveable electrode is stuck or not, and if it is, soak the entire igniter in your favorite rust buster for a month. Upon removal from the magic solution extract the two cotter pins which may have to be broken off and drilled out at a later date.
After the above, remove the lock nut and washer from the taper pin and remove the pin from the anvil. Next, gently tap the moveable electrode with a brass hammer, or piece of wood being hit with a hammer. It is easy to mushroom the end of the electrode if hit directly with a steel hammer. If all the above fails, use the torch, 'heat wrench' and repeat above. Using this procedure I put the body of the igniter in the vice and heat all parts the moveable electrode is in contact with. Sometimes it is necessary to repeat all the above steps to free an extremely rusty electrode.
If the moveable electrode is not stuck, the removal procedure to this point is extremely easy.
The last step in disassembly is to remove the nut, wire clip (fahnestock clip), and washer from the fixed electrode, then remove the mica washers from the outside of the igniter. Remove the fixed electrode from the body by pushing on the end with a wood block. It may be necessary to tap on the block, gently. Hurray!!! The igniter is apart, and this was the most difficult part if the electrodes were stuck in the body.
You should now have the following parts: igniter body, taper pin with nut, moveable electrode, fixed electrode, anvil, hammer.
Thoroughly clean all the parts and check for cracks or breaks.
If the igniter body is broken, it can be repaired, but with extreme caution, as the outboard bearing needs to be in line with the inboard bearing hole. My procedure is to grind a V shaped groove in the break, place an exhaust valve from a tractor in the bearing holes to form a perfect alignment, preheat the igniter body, and either nickel weld or braze very carefully as to not heat draw the parts out of alignment. Upon completion of the welding, I place the parts in Portland Cement powder to slow cool. If you are not familiar with cast welding, it is my suggestion you have it done by a professional. Generally the rest of the parts will be satisfactory for reuse, except the igniter points. Check carefully for wear, burn marks, or misalignment if you intend to reuse the same points, but replacement is the best bet.
Remove the old cotter pin parts if they are still in the moveable electrode.
Next is order time for parts which will include, springs, mica washers, points, and fahnestock clip. (Look through GEM and you will find several excellent suppliers of these parts for about fifteen dollars total).
John Deere igniter reassembly
Get out the valve grinding compound and expect to stay busy for a while. Apply the compound to the moveable electrode and seat in the igniter body and using a back and forth motion get with it. Grind until you are absolutely sure the seat is good, then grind some more. A good fit is essential to prevent having to take the igniter apart and repeat this aspect of the process.
Thoroughly clean all grinding compound from the parts, and you are ready to make an old igniter "new."
Take both electrodes and remove the old points by drilling a one-eighth inch hole through the old points shank, and they should fall out. If not, give them some persuasion with a punch. Insert the new points and peen the end of the shank until the points are tight.
For reassembly place the removable electrode through the body inboard bearing, and slip the anvil, followed by large spring, followed by the hammer over the shaft of the electrode and then push the electrode through the out board bearing. (This is the exact opposite procedure you used in taking the electrode out of the body).
Place one end of the large spring over the knob on the igniter hammer and put the other end near the hole in the anvil and get the taper pin. Carefully hook the spring around the taper pin, making sure when you install the pin, the flat side is congruent with the slot machined in the moveable electrode. Put the pin in place with the spring hooked over the end, followed by the washer, nut, and tighten. This procedure can be reversed if you find it easier to put one end of the spring over the taper pin first, then over the hammer point.
Get the small spring (torsion) and place it over the moveable electrode, outside of outboard bearing, and twist the spring so a cotter pin can be inserted through the electrode and through the other end of the spring. This is the part that most often causes problems, because it is easy to twist the torsion spring the wrong way when inserting the cotter pin, but if this happens, just remove the cotter pin and twist the spring in the opposite direction.
Take the fixed electrode and place several mica washers over the electrode and insert it through the igniter body. With the electrode pushed up tight to the body, check to make sure the points are aligned. If not, add or remove some washers to accomplish alignment making sure the points mate properly.
Place several washers over the electrode shaft on the outside to the igniter body, followed by a flat washer, fahnestock clip, locker washer, and nut. Tighten, but make sure the points are properly seated with each other. If not, modify the aforementioned procedure.
Apply some thin oil to the bearings and let's check it out.
The points should be seated evenly against each other, but when you move the hammer with your finger, a small gap should appear between the points. I like to have a maximum of 1/8 inch or less gap. (A sixteenth is perfect). If this gap does not appear, then you may need to take a second look at adjusting the torsion spring.
Paint the igniter to your desired color (pink not recommended), put on a new igniter gasket and back to the head it goes.
As you can tell from the above, I am not a professional at rebuilding, but do have 35 John Deere engines and have gained some experience.
Good luck, and keep green.