The mixture screw is what you were turning while holding the gauge. This adjusts the fuel to air ratio during idle and just off idle right before the main metering circuit takes over. As you went in with the screw you leaned out the mixture enough the engine couldn't run. Backing it back out the mixture became richer. As stated above, you should be in the 1 1/2 to 2 turns out from the seated position of the screw.

If its starting with out touching the throttle you are very close, a 1/4 turn either way should effect its starting, better out, worse in.

The throttle shaft is where the linkage hooks to, if it can be wiggles around a lot, then the bushings are worn out. No need to remove anything to check it.

Joe

1937 Chevrolet Inline-powered Streetrod