Many thanks your reply.
C1841 has Frederick aged 59 years, and C1851 shows him 60 years of age

Obtained church microfiche records, via Family Search, of Alverdissen which were really difficult to read. Also had a researcher from FS in Utah look at same. The surname Burghart appears spelt sometime with a 'd' or a 't' but again it is very difficult to distinguish. Other spellings were BORCHARD BURCHARD. Christian names were Gottried, Friedrich, Johann, Wilhelm.
Back in 2008 I was told by distant family members that they visited the Church in Alverdissen and found from the church records that Frederick was born in 1791 and his father was a solider in the local 'schloss' (sic). However, they didn't supply any documentation nor the actual date of birth/baptism, and since being given that information, they haven't made contact since. Some months later I contacted the Church and was told they held no such records

So, if born in 1791 he would have been 62 when he died, (and not 74 as shown on D.C.) however that would also nearly matched the age of 60 shown on C1851. If going on C1841 age, he would have been born about 1772 and therefore about 81 years when he passed away.