No matter what model that is a vintage bow, having steel cables with teardrops for string attachment. I don't know the model or just what kind of wheels I am looking at, but they may be Sonic wheels. If you look close it does have a draw length module held to the wheel with two screws. One is hiding behind the fork of the limb. You need to remove the module and see if there is a number/letter designation on it. It might have something like 6X stamped on one side. This might even be visible on the other module without removing it. If so then you would need a 5X (one number smaller) to shorten up by one inch, 4X for two inches, and so on.
From that point on you'll have to do a search for the mkodule you want. Martin won't have any. Best bet would be the classifieds on Archery Talk, Ebay maybe. It's a long shot but the only one you have at this point.
In any case, let us know what you find on the module and we may be able to help further.
If You're Not Living on the Edge You're Taking Up Too Much Space
Martin/Rytera Staff Shooter
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