My John Manson walls: Leith census

[bmanson]

1. My ggg grandfather John Manson has been found on the 1841/1851/1861 census living on Giles Street and later on Sheriff Brae.
1841 Census (Partial): Address: 58 Giles St So. Leith
MANSON   John   M   34   Blockmaker Journeyman   
MANSON   John   M   12     Midlothian
We know he died between Jan, 1866 (death of a daughter at 13 Sheriff Brae) and Dec. 1874 (deceased at time of marriage of a daughter).  We have never been able to locate a death certificate.
2. Son John (above, b.c. 1828, Leith) was not on the 1851 census. We have not located him.
3. Nephew John (b.1859,Glasgow) has never been located (probably went to sea), even though his father Robert (living again on Sheriff Brae) has been found on both the 1881 and 1891 census.
4. I am not even going to talk about my gggg grandfather John Manson who married Margaret Robertson in Edinburgh in 1790; witnessed a daughter's marriage in Leith in 1814; and for whom no death record has been located as yet, but we are confident he died in South Leith.
Help?