Set screw or did installer not install correctly?

[mayhem69]

Hi, i am cleaning my wood stove pipe for the first time. Please see pics.. I removed 6 screws at the middle and bottom of my 2 pcs. of 6" pipe. The top section slid down. There is 1 screw at the top that did not get screwed through the tailpiece. There was just a dent where it was. There are 3 holes on the top pipe but the installer only used 1 screw in the front, which was not screwed through the tail piece, see pic. I am thinking it might be just a set screw? Or does it get screwed through the tail piece??

 

[begreen]

The installer should have predrilled a tap hole for the screw on the inner piece.

 

[mayhem69]

The installer should have predrilled a tap hole for the screw on the inner piece.

That's what i was thinking. There was a dent there when i removed it. Could the smoke be going into my ceiling from this? Also he only did one screw in the front. The other 2 were not done. I guess this is not a big deal? I saw another guy on youtube with a big hose clamp around the top of his.

 

[begreen]

Each joint should have 3 screws, 120º apart. If there is ever a big puffback, a securely attached flue system is greatly appreciated.
Negative on the hose clamp.