I have some "notes" (not from me, but someone on this forum, so you could
search the site for the creator) from when I worked on my LT.
Also, information regarding the grounding plate.
Hope this helps.

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The points polish up nicely with croakus cloth or fine sandpaper. The weak point of the ignition system is the distributor. On the inside of the flywheel hub, there is a bakelite drum with a brass patch. As this brass patch comes around it contacts a brush finger that grounds out whichever plug is not firing. These fingers can be a bit fragile, or sometimes they get mis-adjusted and don’t contact the drum. Another problem is carbon streaking on the bakelite causing it to short out both sides. Points are set at .020 inch and the Champion J8J (modern CJ8) plugs are gapped at .030 inch.

Cooling is pretty straight forward. It’s not the pressure-vac system. Instead, there is a plunger pump just above the prop. There are a few possibilities for problems here. Sometimes the eccentric on the prop-shaft can wear a hole in the bottom of the plunger. Just solder a penny over the hole. Sometimes the ball check valves can get stuck. Clean them with liquid wrench or PB-Blaster. There should be a tattle-tale pisser on the elbow on the port side where the cooling water enters the powerhead. Yes, I know the water pissing out is warm. It just came up a tube in the exhaust and picked up heat along the way. It will still cool the powerhead just fine as long as it’s water and not steam coming out.

Carburetion is a fun spot on these motors. Think of it as 2 carbs. Carb number one is between the center main bearing and the tank. It sorta looks like an inverted "Y". The top branch is an oil return line from the top main bearing. The port branch is your mixture needle. The starboard branch is a fuel line from the float bowl. This carb operates throughout the operating range of the motor and needs to adjusted first. A good starting point is 3/4 of a turn out from lightly seated. Carb number 2 only works whenever the throttle butterfly is open-that is, from "START" of to "FAST". After you get carb 1 adjusted for smooth idle, open up the butterfly and tweak the high speed needle. Again, a good starting point is 3/4 of a turn from lightly seated.

There’s no reed valves o the motor. Carb 1 feeds the mix into the crankcase via a rotory valve machined into the main journal. Carb 2 feeds into the crancase through a third port. 1/2 pint of oil (or more) per gallon of gas.

OK, now you got both needles open 3/4 of a turn, you’ve put the right mix in the tank and opened the fuel valve and the vent in the gas cap. Wrap the rope around the flywheel clockwise. Push down on the plunger about 5 times. This squirts gas directly into the throat of carb 1. The owners manual says 3 licks on the primer, but it seams to me the first few licks don’t do anything but fill the fuel line. You’ll hear the gas squirt. Now make sure you’re pointed towards open water and pull the rope. It should fire. If it starts to act like it’s starving, hit the primer another lick. Flooding? Slide the spark advance over to "FAST". And you’re off and running!
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Yes, the brass contact is grounded to the flywheel under the bakelite plate
with a little spring. Most likely it rusted away.
I carefully ground off the bakelite plate’s rivet heads to
get mine apart, then epoxied the rivets when re-installing it.
Perhaps someone will have a better idea. Photos would help
when you get to that point.
I just found photos of my HD-15, with the same type of magneto……
Make sure you mark the orientation of the bakelite plate before
you remove it.

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HayFever, Brillman.com use to sell the sparkplug boots, and the wire core sparkplug wire,
or you can find them on Ebay……..
https://www.ebay.com/itm/2-Spark-Plug-boots-7MM-for-outboard-small-engine-chainsaw-lawn-mower-NEW/133282075197?hash=item1f083b123d:g:gboAAOSwW2hd~-le
They’re sometimes refered to as the “sparky” style boots.
Glad you got the power head freed up! and no fire departments were called, lol