Put spool on, hold on with threaded nut, push and twist on spool cover.
If you're missing parts you can get the kit from ALM Manucturing
part number ALM BD030
http://www.almmanufacturing.com/index.php/products/garden-machine-parts/grass-trimmers/black-&-decker-grass-trimmers/item/177-alm-bd030-spool-housing
Richard
April 2015
I can answer this question...
my black andDecker trim and Strom 565 the full spool including bolt keeps ?