Small Engines (Lawn Mowers, etc.): starting a poorly maintained snowblower, internal passages, high octane

Question
Hi.  Your tip about cleaning the carb may be the answer to my question, but I'm not sure.  First, I don't know what tag wire is, and second, I don't know whether your suggestion requires disassembly of the carb or can be done w/o disassembly.

My snowblower worked OK last season.  I left it sitting all year, always thinking I would get around to doing some work on it and not doing so.  Now its winter and time to start it and it won't start.  

First I should mention that this is a 5-8 HP tecumseh engine, with electric starter.  

So far, after a couple of friends have looked at it and offered opinions, I've drained the gas and replaced it with high octane, with a little carb cleaner added, and a little dry gas.

One of my friends also pulled the plug and showed that it was generating a spark, but said the spark was weak and inconsistent.  I've scraped the plug a bit with a narrow file, both surfaces.

When I try to start it, the starter chugs away. and eventually gas drips down the handle of the choke -- at which point I stop trying.

I've played with the needle valve on the carb, running it all the way in, all the way out, and about halfway between which is where I think it was before I started playing with it.

One friend recommended warming the engine block with a block heater (which I don't have).  Another suggested careful use of a torch (which scares the heck out of me) or a hair-dryer; I was thinking of trying a small ceramic space heater, but am not sure if there's any point out in the weather.

Is it possible that gas is not getting from the carb to the cylinder, and that that's why its dripping out the choke handle instead?

Any suggestions?  Thanks very much.

Answer
You should remove and thoroughly clean the carb as I suggest.  A piece of tag wire is a small wire (like the one laminated into a garbage bag tie) that you can use to push through all of the internal passages.  There is small passage up inside the main stack of the carb (threaded stack that float bowl nut threads into) that will require a small 90° bend in the tag wire to get clean.  Then follow up with aerosol carb cleaner.  Fuel dripping is caused by the needle and seat not sealing (as you know) but varnish from old fuel can be hanging up the float assembly as well.  Make sure everything is spotless inside the carb before you proceed.  The float should be parallel to the float bowl mounting area of the carb body when you tip the carb upside down.  Hope this helps.