Visible crew/equipment: When the Conners' friends come over and say "Hey Jailbird!" to Dan, a microphone can be seen coming down and going back up in the top left corner.
Visible crew/equipment: While Darlene is at the jail to post bail for Dan, when she says, "I guess I should prepare you for all the things that have changed," the boom mic casts a shadow on the wall, at the right side of the screen. (00:04:25)
Answer: Clearly, the only person who could truly answer this question would be a set designer for the series, or someone else directly connected to the series who would have this kind of detailed information. I looked on IMDb.com and Cheryl Lanner is credited as set designer through 1997. I quickly found her Facebook page, and I directed your question to her. After some time, Ms. Lanner has replied as follows: "I decorated the last season 1/2 but after 9 seasons the sofa just plain got worn out and had to be repaired from 8 years of usage. There was a board put on the sofa but as I've said, it was due to so much usage. If they had back problems I was unaware of them, but you can be assured that if that was the problem it would have been fixed immediately. Take care Michael!"
Michael Albert