Adrian,

The carb is a used WT456 purchased used for $20 on Ebay.

Here's some pics that show that sensor mounting bracket. Unfortunately, with the viewing angle, you can't see the two washers under the mounting screw that were needed to keep the sensor off the bearing housing. Couldn't just file down the aluminum because it was the actual hall sensor that would have touched first.

Too bad the video is kind of dark. Probably won't be another one....that water has already passed under the bridge so to speak.