I have an Oscar Schmidt Autoharp with a brown plastic cover over the chord bars. I purchased it in 1981 or 1982 through the Sears catalogue. They only put brown covers on them for one or two years, otherwise they used black. If you need to replace the cover, you will only be able to get a black one. I have taken the chord bar cover off and there are small springs under the bars, but with a modicum of care you won't lose any springs removing the cover. I seem to have springs go SPRONG when I rearrange the bars. Springs are replaceable also. For a quick temporary fix, you can use a spring from a ballpoint pen. Cut a bit from one end of the spring, so it is the same length as the original, and place it on the peg with the cut end facing up.
Good Luck.