Thumper's site looks good. When he gets old enough, he'll use bigger type so he won't have to use a magnifying glass all the time.
Since I could barely read his writing, I'll put ti in other words;
There are 2 TDC's. So, you have to take the little panel off the side of the engine where the decompressor cable goes in. There is a small rubber O-ring under that nut- KEEP TRACK OF IT. It may stay on the cover. If so, take it off and put it back in the nut so it won't get mangled when you put the nut on again.
Now, take out the plug and put something long in there- like a pencil. The reason you want to hold it verticle is that if you let go, when the piston jumps up, it may trap the pencil (or whatever you use) between the head and the piston. (If you use an allen wrench or screwdriver, they may harm the aluminium head and/or plug hole)
I rotate the engine by putting it in 4th or 5th gear and jerking on the wheel. That way you and work the wheel and hold on to your dowel at the same time. The dowel will come up high twice, so you have to go to the other side and try to rotate the push rods. If they BOTH do not turn relatively freely, go through the cycle once more. At the proper TDC, both push rods will turn easy.
How I adjust; hold the 13mm and 10mm with the left hand after you loosen the stop nut. the adjustment is with the smaller 8mm nut at bottom. It is VERY sensitive, so don't go all gorilla- sublty and nuance are good here. After moving the 8 whichever way I want it, I hold it and the 13 still with my left hand while I tighten the lock nut to the left with my right hand. The push rods should rotate with pressure from a finger, but not spin fast if you flick it. If it's really hard to move, it's too tight.
When I put the sidecover back on, I out a little grease or oil around the edges to help seal them and to prevent binding the next time I take it off. Don't forget the keyhole-looking hole goes on the right side of the rubber gasket.
I sure hope that made sense. This type is also too small for me to re-read and make
corrections.
With the trransmision, I would try changing the oil first. I put a good synthetic in there.