Reconstructing Maintenance Logbooks

Original owner passed on and original factory logbook was lost at that time.. Registration is current and airworthiness (standard) certificate is present. There are five ADs that apply by manufacturer and type and a sixth that may apply but until inspected will not know for sure. What has the FAA typically required or accepted on these and is there an AC that covers specifics to sailplanes? The 'official' maintenance manual reflects a 3000 hour maintenance inspection process ("available on request from the manufacturer") which can extend the life to 6000 hours. It seems unlikely that this bird has even touched 500 hours much less 1000 and certainly nowhere near 3000 hours.