IHC Magneto Timing

I removed the gear set that positions the rotor bug and need to get it back in register. I see no markings on the two mating gears. Do I just position the gears so that the bug points to #1 cylinder wire as close as I can visually when the points are just opening? Then fine tune it at assembly by means of the slotted mounting holes on the body?
Seems to me they should have put a marking on these gears!
I have another mag that does not show continuity between the secondary outlet and ground which I guess means the secondary coil is open. Is that the normal mode of failure?

They ARE marked. Full information is on Pages 51 and 52 at this link:

http://www.cleancomputes.com/Cub/Blue%20Ribbon%20Service%20Manuals/GSS-5035%20Service%20Manual%20Magnetos/Page%2052.jpg



The coils can fail in various ways from "opens" to "shorts" to "leaky insulation".

Thanks Bob....That link is amazing, don't know how you ever found it!
One other question since you seem to know these. It seems to me that there is no way to time the mag with the engine for both high speed and starting. There is no "advance" mechanism like on distributors. So you can set the mag to snap at the starting point or else you could move the mag to set the spark at the full advanced high speed point. I think the manuals say to set the mag to snap at 0 degrees advance, but then the advance at high speed will be whatever occurs at that setting. I guess the "advance" from 0 degrees to 30 degrees full speed is purely a function of the dimensions machined into the mag components. Am I correct?
Thanks again for the great link!

Magneto timing is fixed at 35 degrees BTDC. 0 degrees at cranking speed, when the engine started then it jumps to full advance. You SHOULD time the mag so that the impulse trips at top dead center on compression stroke, that is how the IHC manual says it should be done.
Nebraksa Kirk

Kirk has it right. The mag at rest has no advance and is set up at top dead center. Running, it is a flat 35 degree advance at any speed, no variability as in a battery igntion distributor.

There is no scale on the motor to check and set running advance with a light as you might find on a car motor. You don't say what your tractor is. If it has a 113 or 123, it takes some measuring and figuring, but you can make your own marks -- one on the timing cover and two on the crank pulley, one at TDC (for static timing of ignition and valves) and another at 35 BTDC just to check the running igntion timing. If it's an H or M, it already has the first two marks and you only have to determine where the spot for 35 degrees is and mark that.

Only caution I'd offer about moving the mag to advancing your running timing any further than where the mag runs is that it will also advance the static timing. Any advance on a static motor can cause a handcrank to kick back viciously. If you have any plans about using the handcrank, you want to develop some real good discipline about doing that safely, which isn't a bad idea anyway, even when set up at TDC.

Set it up by the book and see how it runs. If there's problems check back.