There are several things you need to do to check for proper operation of the throttle lever.
First I would loosen the screw that holds the throttle cable outer jacket at the carb. You should have the air filter removed for this so you can see what is happening.
Move the throttle lever (on the dash) all the way up so that it should be in the choke position. Now, at the carb, move the throttle cable outer jacket so that the choke is closed. Now hold the jacket in this location while you tighten the clamp screw.
Now you can move the throttle lever to the idle position and observe that the choke is open and that the throttle cable operates the governor/throttle levers.
Just one more thing about the LX178. The throttle cable, in most cases, rest against the battery. On the LX178 that I worked on, the fumes from the battery corroded thru the outer jacket on the cable. This made the throttle operation very hap-hazard as it did not move the throttle in accordance with the lever.