[newell_0]

10 psi a minute is a big air leak!  First of all don't assume it is just one air leak.  It may be many small ones that add up.  Your coach is of the age that air leaks begin showing up.  The only way I have found to successfully find air leaks is to start by organizing your search which necessitates some understanding of the air system.  Since you are not doing the work, does Holland know the air system on a Newell?  if not it is my opinion you may be wasting your money.

I would start with the 12V air system.  With the 110V air compressor off and the 12V air compressor on how often does it run.  If not often then you have eliminated the 12V air system.  If the 12V air pump runs often then you may have focused on where you will find your air leaks and save yourself many hours of looking where there are no leaks.

To try to form a list of things to check will not lead to good results in finding air leaks has been my experience.

You might read these threads.  I spent the winter finding and correcting air leaks on my coach.

http://newellgurus.com/showthread.php?tid=2705

http://newellgurus.com/showthread.php?tid=2690

Good luck......................................

Good suggestions!
It was pretty clear to me that they (HMH) do not have an understanding of the air system for the Newells. You are right, it will be a waste of money at $120/hr to do random checks. If they don't find it today, I'm not going to have them continue searching!
Thanks for the links, too. I'll look at them as well!