Is there an easy way to repair SAM hive?

ThinkPad running XP Home Edition reboots endlessly >path to lsass.exe not found< The Repair Console won't work because SAM is corrupt, asking for a nonexistant password. I now have the HDD running on another XP computer, no virus detected by Malwarebytes. Is there an application available other than the RegEditor to repair/replace the SAM hive? It looks like there are plenty of restore points available.