after some digging around this is what I found:

It should be noted that on some models you will need a T-20 security head (star-bit) driver to access the brush assembly. Of more importance, you will need at least a 3 inch bit, or single driver with a 3-inch stem, but do NOT try to use a 1/4 inch hex bit extender as the connector shank will be too wide to fit down the narrow screw wells.

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https://www.youtube.com/watch?v=zkDeWuXb...

same issue here… must be on the later models.. looks like you need a special tool to get these screws out… look like hexagonal screw heads…