Main thing is to NOT let the dealer rush you thru the PDI.
The longer it takes you, the better chance you may find something. SO, start the PDI first thing in the morning, NOT in the middle of the afternoon.
Main issues on mine was the bathroom door was mounted crooked and it was easy to see into the bathroom between the door and the strike plate and strip (when standing in front of the bathroom door inside the trailer).
Made the dealer fix this. Noticed there were screws missing on the cabinet doors below the entertainment center. Dealer installed required missing screws.
Laid down under the slide out and had DW shine the flash light around all the seams/seals. Saw dome flashlight coming out the the back bottom seam. If light could get out, water could get in. Dealer sealed that. Noticed slide was not the same tightness on the front and back when up against the seal when closed all the way. (about 1/2 inch difference) dealer adjusted the slide.
Make sure you check the roof and slide out tops for any small tears or slits or possible nails/screws getting ready to punch thru..
Found a lot of metal shavings in storage locations, in the under bed storage and anywhere else I could access. INCLUDING in heat ducts on the floor. Made the dealer clean these out with a vacuum cleaner. (This should have been caught at the factory)
Pressurize the water lines (water pump and hose, yes 2 different ways to pressurize the water lines.and run water. Make sure there are no leaks. We had some water leaking around the crimped fitting at the hose connection to the pottie, it would leak a little as we held the foot pedal down to run a long flush. Dealer put a new crimp fitting on and that resolved the issue.
When the dealer saw I was starting to be very through with the PDA, he complained that they only allow for 1 1/2 hours for this. I told him he is free to go do whatever else he wants to do and we will come get him when we were done or he could watch and as we found issues, start rectifying them right away. Took me about 5 hours to go thru everything. DW followed me with paper and pencil and took photos. Everything we found was thankfully able to be taken care of that day as the issues were found.
Tested all the electrical outlets and USB charging ports. Tested all light including microwave light and fan.
Found a area on the floor near the bathroom entrance where a screw was pushing up thru the flooring vinyl. (no hole yet) Dealer made a small cut along the floor seam, took the screw out and put glue in and a new screw. Used seam sealer on the floor and 3 years later still looks as good as new.
Like mentioned above, YES, a flashlight (bright one) helps see things on the roof in the daylight too.
This may be the link OldManAZ was referring to.