Hi
I presume you are looking at the Bishops' Transcripts on family search. I tried to construct an index for the Chester-le-Street images when I was looking at them a few months ago. In the 1765 to 1821 set of 1,083 images, there seem to be very few marriages. I indexed from image 1 to 500 and the marriage sequences that I found were:
Images Marriage dates
200-201 2 Dec 1783 - 21 Jun 1784
316-318 16 Jan 1798 - 21 Jul 1798
320-320 4 Nov 1798 - 15 Jan 1799
322-322 9 Jan 1799 - 13 Jun 1799
341-341 8 Nov 1800 - 15 Nov 1800
500-500 11 May 1805 - 1 Jun 1805
It looks as if somebody researching the originals before Family Search photographed them has extracted most of the marriage records.
The Bell index does not show any signs of these gaps so I presume there is a more or less complete set in the parish records at the Durham RO. You can get to the Bell index files via the Genuki site at
http://www.joinermarriageindex.com/pjoiner/genuki/DUR/ChesterleStreet/index.htmlThere are quite a few marriages indexed fo 1792 but the index only shows the date of the wedding and the names of the bride and groom.
All the best
Gobbo