The lock is easy to take out. The lock has to be disassembled which is a little more difficult. If you know someone with a little more mechanical skill, you may want to have them do it. I had no experience and had no problem. If you do it yourself, take pictures with a digital camera so you can see how it came apart. Might help putting it back together. In any case, you will need a professional to put the new lock since, I understand, it requires modifying the opening in the door.
As for taking the lock out, there are three screws on the inside and two on the door edge. The disassembly of the lock itself is a little more complicated. But not too much.
Look at it this way.
You are going to spend a bunch 'o money for the replacement and installation. Here is your opportunity to expand your knowledge about your unit. You have nothing to loose and everything to gain. GO FOR IT! GIT'r DONE!
If you want the users and owners manuals, I have them on-line for my 78 Excella. Here is the link
1978 Airstream Excella 500 Manuals
You can download them in pdf format.