Small Engines (Lawn Mowers, etc.): Carb rebuild snowblower tecumseh 5hp, rule of thumb, needle valve

Question
I am pretty sure I need to clean or rebuild the carb on my snowblower.

Previously I could start it by putting gas in the spark plug hole. Then it will run.
Now it runs for short time and dies.

So I am sure it is carb related.
I could take it apart and clean it. But I would like to be sure I can adjust the many screws etc.. correctly. Is there a manual or some rule of thumb on these.
I have heard you mention only the needle valve 1 1/2 turns from seated. What about the others.

Is it worth doing a complete rebuild and were can I obtain the parts/manuals

Answer
You can start any mixture screw at 1 1/2 turns out from lightly seated.  There is only one other mixture screw (low speed) on a typical Tecumseh snowblower carb.  Any other screws are limits for throttle travel and idle speed....if they've never been adjusted, leave them alone.  If they have, try to put them back where they were (paint missing will give indication)  If the carb has a blockage, you will notice that no amount of adjustment will have any effect on the engine performance.  From what you have described, however, the carb does need to be cleaned using a piece of tag wire and follow up with aerosol carb cleaner.  Pay close attention to a passage in the main stack....usually requires you bend a small 90° elbow in your piece of tag wire to access it.  Parts are readily available from any Tecumseh dealer (depends on your location)  Hope this helps.