It's been a long time since I last used WW 1.9 but you shouldn't have to do anything with the .sco files (assuming the old .sco files are still in place). When the students work on a problem which they worked on, their new scores will be appended to the .sco files. When the set is past the due date, the set should be scored using the .sco files (there is an option or script to do this --- I don't recall which). Obviously you can test this on your test server.
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WW 1.9 - Can't find record with psvn = 143819 in the database
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