Track Inspection Train on the NTS&B - Updated

A screw came out of an engine I recently purchased, so I had to search the Helix Loop trying to find it.  After looking for a while using a ladder and flashlight, I decided there must be an easier way.  The camera car that I helped Train Dr Ted build worked well, but did not shed enough light close up, so I had to add another light car to the mix.  I had to use a TMCC engine so I could stop and start it without affecting track power which also powers the camera.  Although I still didn't find the missing screw, it was sure a lot easier this way than lugging a ladder around and crawling all over the layout.  Here's a couple pictures to demonstrate the process.

TMCC Controlled GG1 pushing search light car and TV Camera Car

Me diligently searching for the missing screw

Since I hadn't found the screw I decided to revisit Plan A to find the part, which was to use a magnet on attached to a train car.  My original idea was to set the big magnet I had on top of a flat car.  The car was too high, and it would not pick up anything.   I then looked for smaller magnets that I could mount underneath the car, but didn't have any.  I was discussing my problem with a friend, who mentioned that it was too bad I couldn't hang a magnet off the front of an engine.   Although I wouldn't hang one off an engine, it did give me the idea of hanging one off the back of a car.   Although it was very crude and I had to make adjustments so it would clear the helix, it turned out to be effective and I found the screw.  After that it also dawned on me that I could have used a depressed center flat car.