One more maybe useful comment and one more questions to gurus:

select RDB$RELATION_ID, RDB$FORMAT
from rdb$formats
where rdb$relation_id=661 /*Damaged table*/

RDB$RELATION_ID RDB$FORMAT
=============== ==========

661 1
661 2
661 3
661 4
661 5
661 6
661 7
661 8
661 8
661 8
661 8
661 8
661 8
661 8
661 8
661 8
661 8
661 8
661 8
661 8
661 8
661 8
661 8
661 8

Funny. Question: what if I simply update this company of 8 to
seauentntal values? Didn'it break some logic for further filling for
another tables? Some system generator etc?

Best regards.