A decent guitar repairman should be able to adjust the action on a dulcimer no matter if it was made in China or in the '70s. If you can't find one willing to do it, you might check your area to see if there is a luthier's club. I belong to one, and we've been known to take in people's instruments and work on them for free to demonstrate the methods. For instance, I volunteered to a neighbor to adjust the action on his '70s Japanese-made banjo. I took it to our meeting and we all got a good laugh out of the lopsided glued on nameplate ("Aquarius") and the cheesy truss rod cover that covered nothing, but by the end of the evening I'd learned a valuable trick for adjusting the action at the nuts (how to gauge when the slots are deep enough without filing them too deep). And my neighbor had playable banjo.