Found during a PM of an older York RTU. The blower section had dozens of loose screws in it. Think maybe someone spilled a container at some point and was too lazy to pick them up.
The next thing was the draft motor was running continuously. I found that the unit had a failed draft motor controller (York's over-engineered draft motor relay setup). Some investigation found out someone that used to work for our company found this originally. Instead of fixing it right he just threw a set of jumpers across the relay and called it good. Sad thing is two others have been there since and didn't do anything about it.