am fighting ally corrosion at the mo on the series 2 restoration , especialy near steel to ally joints bolts etc, even loose fixings will cause earth problems leading to elec galv corosion. the ally should be polished clean with a sander etc then aluminium acid brushed on and washed off , that wil get shut of the white fluffy stuff, then dry up and spray with the acid etch primer, as a wash prime, spray over with acid etch everytime a jobs done , so as to be sure of full coverage, paint wint stick to ally if youve missed a bit