While you wait for answers, we may have found some information which could help you.
Click here for Spool Black DeckerGrass trimmer not working correctly?
How can I spool on my Black & Decker Strimmer GL220?
how to rewind the spool on black & decker strimmer gl720?
How do I replace a broken drive belt on my electric Black & Decker Strimmer?
Drive belt?
Black & Decker GL540 trimmer nylon cord unravelling how can I fix that?