Engine rpm excessive when using

If the RPM is running away or fluctuating badly, I’d stop running it until you find the cause. A small engine overspeeding can do some serious damage. On these snow blowers, I’d check the governor linkage and spring first. Make sure the linkage moves freely and hasn’t come loose, bent, or been installed in the wrong hole. Also check that the throttle plate isn’t sticking.

After that, look for a vacuum/air leak around the carburetor and intake. A lean condition can make the engine surge.

Don’t try to control the RPM by manually bending the governor arm. If you can post a picture of the carburetor/governor linkage, we can see if something is out of place.