Here is a factory service manual to keep your Edison CD alive and well.
Service procedures are similar for the C,CD,and CDH as described on page 15. Parts info to follow.
Be very careful with the metal sealing rings that hold the bearing cages and grease in place. They are made of unobtainium. Gently pry under the bearing cage with a screwdeiver and replace with the end of a deep socket after washing and repacking bearings. Check the condenser for electrical leakage with an automotive cindenser tester. They were fairly robust but if defective one can use an automotive device in its place as shown on photos below. This mag went swimming and the condenser literally rusted away in spots. One may need to splice and extend the condenser lead to reach the terminals.
Line 4Ab describes an important issue with this model. It is possible to slide the coil fully foreward when installing causing the end to tip up and not sit flat on pole shoes. This causes an air gap and a wimpy mag.
Here is a major source of grief with this model. When the coil is set in place and slides full foreward till it stops the end tips up and leaves an air gap between the coil and magneto pole shoes as shown on the left. This will cause a wimpy spark. The best way to install the coil is to let it set down flat on the magneto pole shoes and slide it foreward, then install the clamp and screws so the pole shoes makes perfect contact as seen on the right. This one went swimming and the condenser literally rusted away and was replaced with an automotive device. These work well and usually need to be bent upward slightly to clear the armature gear. Most automotive condensers are .18-.22 Microfarad capacity and OEM Edison Splitdorf devices were .15MFD. When the Edison Splitdorf line was later acquired by Wico their replacement was 0.2MFD.
Visible at the 6 oclock position of the photo is a rectangular hole that is used to index the witness mark on the distributor gear with the mark on the fiber armature gear. Depending on the rotation it will be indexed with R or L. John Deere mags turned counterclockwise and should index in the L position. When you need to service the points do not remove the two lower screws on either side of the timing window. These are only loosened to change the edge gap (described as internal timing in service literature). When adjusting the points always loosen the lever spring mounting screw to allow movement.
Here are the gear witness marks for left hand rotation for Mother Deere.
Internal timing is where we check and set the edge gap once the points are properly set. This gives the biggest bang by optimizing the timing of breaking the electrical circuit when the points open with breaking the magnetic circuit when the edge of the rotor passes the stationary pole sghoe and breaks the magnetic circuit. This adjustment usually stays put in most cases and is probably a good idea to check with a major overhaul. The 110 volt light bulb contraption looks like a good way to get a shock. Better yet disconnect the coil inside, reassemble and use an ohm meter or other continuity tester with alligator clamps connected to the case and the ground switch terminal on top. Turn the mag upside down or on its side so not to engage the impulse then slowly rotate in the direction of rotation till the points open indicated by your continuity tester and measure the edge gap width. A drill bit is a good gage. The breaker plate may be rotated advanced or retarded by loosening the three screws at the 12 Oclock,5 Oclock and 7 Oclock positions without disturbing the point clearance.
This silly contraption is an attempt at a magnet keeper. If you do not have one of these simply charge the magnet in place and rotate the armature backwards so the flux does not go through it but rather through the magnet or do it with the coil or armature removed and all will be well.
The gospel according to Mother Deere specifies that a mag should jump 9MM across a gap with a teaser ar 1000 RPM when in spec.
When reassembling the impulse cup onto the drive hub, the manual describes using a spare magneto armature with the key in the keyway to hold the hub to wiggle the drive cup back in. It is nearly impossible itherwise and will certainly elicit some very discouraging words.