Sarges,
Go easy, we know your frustrated.
I was just looking at the specs on that engine. In the GP series they only show a .42 so assuming that is the engine we are talking about.
If you already do not know, on almost all glow engines, the Air Bleed/Low Speed needle is controlling the mixture from idle to mid-throttle, from that point the high speed needle takes over. I agree, being that you cannot run anything below half throttle you are lean. If it was sloppy rich it would run but either die from being flooded after a few seconds and most likely spitting fuel when you throttle up from idle, but being lean would kill the engine pretty quickly once the Air Bleed screw takes effect coming down from full throttle or going to half throttle or better from idle without spitting fuel.
I found this from a thread a year or so back on setting the Air Bleed Screw. Although he mentions the OS engines the thread was on the TT42GP
take a look in the air bleed hole. The screw should be 1/2 the way across the hole to start with. No two carbs are going to be the same, so 2 turns may or may not be right. Half the hole covered is where most air bleed carbs are set to start with. Adjust it from there to get the best idle mixture.
I've had a few OS FP's that I had to drill the hole out. I wasn't big enough to get it to lean out right. Just a thought.
He goes on to say that this worked well for him. When tuning remember that an air bleed carb is opposite from a low speed needle valve carb. Also, make super small adjustments, I am talking about 1/16 to 1/8 turns at a time, then run it. As was mentioned before, you must have the high speed needle set properly first.
On an Air Bleed, turning the screw out leans the engine while turning it in richens it. You are actually adjusting air, not fuel. This was mentioned before but I thought I would reiterate it. After reading tons of posts on this engine, it being tight at TDC seems to be pretty normal and once it is broken in it will last for ever and the tightness will not be as bad.
If you have already tried this or I am being to redundant, just ignore this post