I'd drain the oil and pull the clutch cover. Get a magnet, one of the extending, nut and bolt retrieving magnets and go fishing. You could stand it up good and shoot brake parts cleaner in it to drive the oil out, get a good light, maybe put a piece of cloth on a wire and sweep it out. Keep up with what you get out. Count the teeth missing from the gear. You need to get that many out. You can also get an oil drain plug with a magnet in it.
If you drain the oil, put the plug in, put a little diesel in it, put it in neutral, roll forward, grab the brake, do that a few times,, maybe that would help move the junk to the front, where you could see it and get it out easier.

Do you have a compressor?
I'm Thinking that with both covers off you can see dang near the whole bottom of the case,someone else can confirm or say no.
Maybe you would be ahead pulling the Right side cover.

Whatever route you take, get cardboard, draw the outline of the side cover, put a slot to stick every bolt in. That way the ones that have the oil seal will go back where they belong and you won't be trying to solve any puzzles about which bolt goes where.
It's better to run the torque pattern five times very carefully than trying to get it tight in two. A thumb on the ratchet head,using the pinky and ring fingers to carefully squeeze the ratchet. FEEEL the tiny,wimpy bolts as they come to their clamping force. You are ahead to discover a leak that you have to address than breaking stuff. The Chinesium is there to cause you pain.
I went in mine several times, never busted anything. One time I had to go back and tighten one.
Bummer about the teeth, hope I helped some, good luck.

Do you have a compressor?
Might not even need one. But they can sure be handy.
I modified a blower nozzle by drilling the tip out and soldering a length of 1/8" brass tubing in it. You can take a piece of 3/8" ID plastic tube and drill a hole a few inches from the end, poke the brass tubing in through that hole and point it out the end, stick the other end in a container of diesel and when you shoot air out the tubing it creates a vacuum and blows the diesel out. Adjust how much how fast by adjusting the distance from the end of your brass tubing in the blower to the end of your plastic tubing. And of course you can control the air flow rate, you can set it up to deliver a fine mist,like cooling an end mill in a drill press or starting a siphon out of a five gallon bucket of hydraulic oil.

The length of brass tubing you use decides how far from the end of the plastic tubing you Can drill the hole. And the hole you drill has to be tight on the brass. I've got about ten inches on one of my blowers, if you do that you can insert it four or five inches back and be able to hold it so the brass tubing is not running across the path of the diesel.
If you're using a small compressor, remember the duty cycle. When it comes on you can use it for a few more seconds, but if you don't stop and let it catch up the life of it will be, how do they say... Uhh,negatively impacted.

If you are going to use your early side cover, it requires machining to fit the late model starter gear.  Otherwise you will need a late model side cover.