I'd tried the lift the bolt and pull the trigger first.
I've got a Model 783. My Google search didn't help much. Anything you could add will be a help.
One of my Marlin bolt .22's, the bolt will fall out when the trigger is pulled, one will pull right out and the other take some force on the trigger and bolt both.
Try pulling the trigger firmly and pulling the bolt back, IIRC you must also leave the bolt at least half way forward while pulling the trigger too, if it's all the way back it won't release.
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