In regards to the engine .....

It is almost 99% just fine. Will need some significant cleaning though.

DO NOT Turn the engine over if you can help it. There is dirt inside, that does damage every time it gets ground between parts.

I had an OS46FX (just like yours, I believe). I buried it nose first into the ground at about 1/2 throttle. Needed both hands to pull it out of the dirt. Just like yours, the needle valve had sheared off.

Strip the engine down. Remove the carbeurator, cylinder head, crank cover, etc. Strip down every part you can get to. It is a lot simpler than it looks.

Here is the breakdown routine.
1. remove both carbeurettor screws (one on each side of carbeurator). Put whole carb assembly into a jar of fuel.
2. Remove 6 SHCS (Socket head cap screws) from cylinder head. Careful, because there is a copper gasket in there. Don't loose it). Also, the head can be mounted in either direction. There is a dimple underneath the cylinder head that is off to one side. Take noe of whre that dimple is so that when you reassemble the engine later, you can put it back the same way you found it. This is not really critical though. Put it in the fuel as well.
3. Remove the 4 SHCS keeping the (now broken) Crank case cover at the rear of the engine. Careful again, because there is another (some type of plastic) gasket. Put it in the fuel.
4. Put your pinky into the back of the crank case, and push up against the cylinder sleeve. It should move with some pressure, and slide up. You will see that there is a pin at the to p of the cylinder, and a notch in the cylinder sleeve that matches up with the pin. Thus, there is only one way for the sleeve to go in. No need to remember it's orientation. It will get tight just before the sleeve is all the way out of the cylinder. This is normal. Just force it gently (that is not an oxymoron). Put it in the fuel.
5. I have found that the piston can only go in one way. I am not sure exactly why though. It is hard to see a difference between the front and back other than at the bottom of the con-rod. One side is slightly larger than the other.... Anyway, with the sleeve out, the piston rattles around a lot, just pull gently at the bottom of the con rod, and the piston/conrod assemply will come out (you have to make sure the crank shaft is as far forward as it goes as well). Just fiddle with it, it is not difficult. Pull the piston/con-rod out the top of the cylinder. Put it in the fuel.
6. Pull out the now free crank shaft. Put it in the fuel.
7. Put the now-empty engine block in the fuel.
8. take the carb out again. Loosen the screw with the spring on completely. Count the approximate number of turns required to remove that screw (write it down). The carb barrel (the part with the throttle control horn on it) will fall out the side. There is a spring in there, which you must not loose.
9. Get an old tooth brush (or someone elses current one ....), and scrub every part using the fuel. Rinse all parts in freesh fuel. The difficult part is cleaning the bearings that are still in the engine block. Use the crank shaft to check them, and just keep rinsing them until the crank shaft spins without being gritty.
10. When all parts are clean, re-assemble in the reverse order of dis-assembly.

I was anxious when I did this the first time (see [link=http://www.rcuniverse.com/forum/When_excited%25%25%25%25_take_a_step_back%25%25%25/m_1188099/tm.htm]My Crash thread[/link]). But, engine is now running fine.

I decided not to spend the money on a new back-plate/crank case cover to repair the broken remote needle mount. Instead, I fabricated ou of balsa and ply a "harness" in which the broken part of the remote needle is sandwiched in. I then attached this to my cowl. I did misjudge one thing, and put the needle on the wrong side of the engine, so there is quite a lone tube between the needle and the carb.

See this picture...

Engine now runs just fine....

gus