| If you want a cheap fix Ozz then buy a decent zip from any department store,you'll need to measure what length you'll need depending on the jacket you want to use.Try and find a zip that'll fit one side or the other and it'll save you attaching both sides.
Sew the new zip to the one thats already on there,NOT through the leather,it'll take about fiftenn minutes to do by hand,you might end up with a short extra length at each front but that shouldn't be a problem.This is the way I got Dainese and hein gericke jackets and trousers to fit each other.
Hein Gericke use a longer length of zip with bigger teeth than Dainese,if I remember correctly a YKK zip should fit. | 
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