[rheavn]

Congratulations on your new coach.  I looked at buying that coach in 2009, but the seller had it overpriced for me.  That is one of my favorite paint designs.  Sounds like you got it for a good price.

My understanding is all the SouthCo latches use the same key.  Try Newell.  If you can't get one I'll make one & send it to you to try.  On my coach the security key is different.  On my coach the radiator fill tank is also a different key.

My 1/2 bath sink was in a similar condition as yours, but mine is stainless.  I did some wet sanding and polishing & it looks new.  Haven't worked with a brass sink, but I would investigate renewing it.

You have a leak in your 12V air system.  I also had an air leak in the bedroom slide seal and it ended up being the shut off valve for the bedroom slide seal which is located under the bed.  Review this thread explaining the 12V air system.

http://newellgurus.com/showthread.php?tid=2674

Since you didn't mention the 12V air pump, I assume you don't run it & the whole system leaks down to zero.  That tells me your 12V air system has a leak.  Otherwise it wouldn't leak down below 60 psi as the 110V air system & the 12V air system are only joined when air pressure is above 60 psi.  A check valve would keep the 12V system at 60 psi if the system was air tight.  Therefore your 12V air pump will never run if your 110V air compressor keeps the air pressure above 60 psi.

If this is clear as mud feel free to ask any questions.....................................