The governor is no longer working
Check you have set it in the right position and the clamp nut is tight
Other than that the governor itself is broken.
Not familiar with yours but in most cases it is easy to have then miss align and on some if you pushed the axel in then the other end can fall off .
How did you replace the seal ?
Did you split the engine ?
I just unbolted the governor arm pulled it forward pulled out the seal put in the new one and put governor arm back on shaft retightened it and hooked everything back to it it cranks and runs just revs too high