I have a 1990 Johnson 150 GT with OMC controls. I need to replace the trim switch that is mounted in my throttle lever. I took the box off, loosened the allen bolt in the middle, and tapped on it like the manual says. The throttle lever didn't move. I tapped fairly hard on it, but still did not come loose. How hard do I have to hit on it to get it off? I don't want to break anything. Is there some kind of trick to get it off?