Vibes n Wisneaky thanks for the info. My chimney is 11x11 clay lined. I am going to see if I can find a Sooteater locally. That seems like it may be a good tool for me. I will also keep in mind the chain method. I still would need to work from the top. Access at the stove is via the 6" hole in the brick to the air box. The chimney exit is about 12-14" in. To inspect I use a large mirror on a long stick. I then shine a spotlight on the mirror and check all I can. I do the same topside. I can look down the chimney but it is a tight fit for my head along with the spotlight.
View attachment 404786
This is the smaller opening. The wooden blocks support the pulley I use. This was a test setup. I have a better support now. The work opening is on the side not visible. Opening is same height but a bit wider. About the length of 1 Brick plus 3/4 brick. Or the left side of the pictured opening extending to the right corner of the brick chimeny. Not much of a work space.