x2 possible crushed tubes.
It seems like you have to rip out the old screws and re-drill new ones next to the old ones. When all is done, tape the seams to cover the old holes.
Another option that some have done is do away with the underbelly. If you do not use the TT in cold weather. Its not a bad idea because you can do easy visual inspections of plumbing and water tanks. You can also close off the underbelly heat duct adding more heat flow to the cabin.
Mice tend to nest in underbellies if you do not do a good job of sealing them up which is difficult to do due to sewer and gas pipes. Use steel wool, spray foam and tape after cleaning the surface.
Here is some other info that might be of help:
https://www.amazon.com/Mobile-Belly-Bottom-Repair-Fix-Underbelly/dp/B00BJ5SPO8thread with PICS on an underbelly fix (I'm sure Jayco owners forum also has the same )
http://www.crossroadsowners.com/forums/f12/replace-underbelly-2786.html
