How to identify and reave 1983 Hobie Harken Main sheet System

Hi, I recently bought a 1983 Hobie 16 and am trying to figure out how to reave this Harken mainsheet system. Could anyone refer me to a video/ diagram? and whats the black switch in the second photo? Thanks!

(I tried to link the image from the same facebook post I've made, hope it works)

https://scontent-lga3-2.xx.fbcdn.net/v/t1.6435-9/226098662_10104355959344456_3361032023359812553_n.jpg?_nc_cat=105&ccb=1-3&_nc_sid=b9115d&_nc_ohc=SLxGq0Tel10AX9wJywh&_nc_ht=scontent-lga3-2.xx&oh=6dc01763e5616a1cc5a40f8db7918dd8&oe=613091B9

https://scontent-lga3-2.xx.fbcdn.net/v/t1.6435-9/227277442_10104355959863416_8362542962650490118_n.jpg?_nc_cat=108&ccb=1-3&_nc_sid=b9115d&_nc_ohc=78YnekWHY1sAX-AYqJK&_nc_ht=scontent-lga3-2.xx&oh=6158e0713c252ffdd0df44c82cae70ea&oe=6132E696

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Dan McNichol
Hobie 16 1983
South Jersey
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dup post, please delete

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Dan McNichol
Hobie 16 1983
South Jersey
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