I like to keep backups of my system, rather than do roll-backs to a Restoration Point, so for years I have cloned my system every week to a partition on a larger hard drive. Last December, I started using an SSD instead of a spinning disc HDD, to store those successive copies of my system. Recently I needed such an old clone, but failed to achieve a bootable HDD, as they all required REPAIR (which did NOT make the drive bootable) when I tried to boot from a clone of one of the partitions. So I bought a new large SSD, created partitions on it, and cloned my system to those partitions; when I clone the partitions back to a smaller drive, they succeed in booting. So something has happened to the original SSD that NOW prevents the creation of bootable clones from its partitions - the new SSD allows it and so should the old one, which has had only 9 months of once-a-week 'work' so can not be 'worn-out'. I'm interested in what damage could have been done - and so if it can be reversed.