[12Ounce]

Yep, I have now reread that post.

The only counterbalance shaft I know of is the one I've already mentioned. Lengthwise ... just over the camshaft and revolves the opposite direction.

I continue to recommend opening up the intake and closely inspecting all plastic parts ... holding them up to the Sun, checking for hairline cracks, ... fit of internal horn-manifold ... air flow blockages .... etc. No telling what you might find. After that, I would drop the oil pan for a look-see. After that, the big one ... heads, etc.. ... ... but hopefully you wont get that far before discovering something simple and easy.