Need good voltage at each magnet and 2.5(+) amps when fully applied via manual lever on brake controller.
That means good battery and tight clean connections to/from magnets and ground on trailer frame
And that one hub that is wear faster......probably adjusted to tight and had a better magnet connection then others.
Each wheel needs to be adjusted initially and then again as shoe linings wear down.
Jack each wheel off ground.
Adjust star wheel on adjuster screw (bottom of drum thru slot) while turning turning tire until tire stops
Then back off star wheel just until tire rotates with a slight drag on shoes.
As for the 8000# vs 7000#
8000# is an upgrade option----------7000# standard.
Literature reflects standard equipment
