unknown dinghy help!

well my main problem right now is the centerboard....it is missing so i have to deal with everything that has to do with the mechanism that makes it go up and down.i could describe you the situation but my english are not that good especialy to speak with terminology.

so i will give it a try.at the center of the dinghy(you can see the photo) there is somekind of box where the centerboard stays in when it's pulled up. it's not the kind of dinghies that has a hole in the middle and you insert the centerboar until it locks down,in this dinghy it stays in the dinghy at all times,you just pull it up or leave it down. after a lot of work i constucted a centerboard that seems to be alright and i tried to recreate the mechanism that moves it(as every piece of its equipment was lost).at my first try i manage to make the centerboard to be pulled up but no matter what i do i can't get it to go down...so the big question is (if you have knowlege of a lot of diferent dinghies an if all the dinghies of this kind have similar mechanism) how in the name of god can i get it to go down?? the only thing that is left is to make a centerboard so heavy that goes down by itself but again needs a way to be locked down because the power of the water as the dinghy sails will bring it up. after all my problem is to do all these things from inside the boat and not have to swim every time