Consider Recoating Instead of Sanding
You may be able to renew the floor by adding a new coat of polyurethane right over the old finish. Recoating takes a lot less time, skill and money than full-scale sanding and refinishing. Recoating works on solid wood, laminated wood and parquet floors alike. But a new coat of polyurethane may not stick to your existing finish. If your floor's finish was applied before the 1970s, it's probably wax, old-fashioned varnish or shellac. No new finish will stick to a wax finish or any other finish that's ever had wax applied to it. Polyurethane might adhere to an old, unwaxed varnish or shellac finish. But these finishes do wear out, and since they're probably more than 30 years old, it's best to sand them off and start over.