Moody dulcimer - early 60's or 70's - needs bridge and stringing advice
Instruments- discuss specific features, luthiers, instrument problems & questions
What Rob said - The bridge will need to be made to fit. Not hard to do. You just need a small slice of hard wood like Maple. Let us know how thin the wood is and someone, or several someones, will probably send you useable bits of wood.
Does the piece of bridge in the slot come out readily, or is it glued in? If glued, run your hairdryer on high a couple inches from the broken bit for a few minutes, then use a small slice of wood like a popcicle stick as a 'punch' to try and drive the the broken bit out sideways.
Back in the 60s and early 70s many makers used a single dowel as a string post like that. If the post is small enough you can open up the loop of loop-end strings and they'll slide right on. Or you can use ball-end strings and run the tip of the string through the ball end and make a loop to slip over the post.
Not having a 6+ fret means you'll probably find it easiest to play this dulcimer in Fingerdance or Noter & Drone style, and not try to play everything from the DAd tuning.
Really nice looking dulcimer. You've got a keeper there!