I had a similar issue. Appears my cable may need replaced as it’s a little hard to move back and forth (sticky). But I was able to get it to the point where the throttle (control) would open the carbs wide open by tightening the cable all the way on the motor end. Before it wouldn’t move the throttle lever far enough to move the carbs at all.
Also issues with mine not staying running, not starting, running rough. Recently mine wouldn’t even turn the flywheel more than a half turn. Replaced my starter yesterday and it fired up after some help with starter fluid. Ran 2 gallons of gas/oil/seafoam mix through it today.