It's not hard at all. You just need to locate a replacement springy (expandable) link for a 1039 bracelet. You have 2 of them attached to the buckle in the lower photo. I don't notice any available on eBay now but they do come up regularly. He is the how to:
http://www.old-omegas.com/bracadd.html
If the bracelet us long enough without the broken link, you can just remove it although the braclet looks short to being with. The links have risen to about $100 each unfortunately but your, very nice, Speedie 105.012 has risen in value as well
Good luck
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