The Battery is new and the connections are good... on an Aero 8 it is the starter, however the symptoms you give are well off needing a new one. A quick fix is to have the electrical terminals on the starter cleaned and it will delay the need for the change.

It was down to the starters sitting round on the crate engines for so long before fitting and bieng susceptable to corrosion when fitted to the Aero.

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