This looks like a modern version for replacement parts for yours. 6-30189 from set 6-38236. it's a 2013 vintage
curiously, they list the two motors at different rpm's
I also noticed when looking at the supplement for the original version, that a foam pad was listed in the fuel tank. Perhaps that was the side to side buffer that was missing from yours. Anyway, you solved that.
Here is a youtube of the horn in the 6-30189