The MacBook Pro that used to be my main writing machine quit working. I knew the end was coming because it had to be plugged in to work at all. For some mysterious reason when I launched it a couple of days ago, the trackpad worked but not the buttons. This problem was there even when I tried a mouse. I have several new machines and no longer work on the old machine, but I always assumed I would take the time to move my content (pics, tunes, documents). Now, it is too late. This is a description of what I did next and the process may be valuable to others.
I kept a backup of the MacBook Pro using time capsule. This approach has advantages and disadvantages. It is easy. I kept an external drive at the office and connected it to update the backup from time to time. With time capsule you can recover a file you have  purposely deleted and you can restore the entire drive if necessary. It turns out you can also use Time Capsule to move specific content to a new computer. This is not the ideal use for Time Capsule, but it can be done.
Here is the approach I used.
1) Migration assistant (an Apple utility) will connect to the Time Capsule content stored on an external drive. There are several options one of which allows the transfer of categories of content.
2) When using migration assistant in this fashion, the software creates a new user account on the new computer. You may not have known that a computer you use allows for multiple users with unique content. Keeping the content separate is the key value here. This guards against overwriting the existing content within a given category (e.g., documents). This is a necessary step, but not the organization that was my ultimate goal. I do not want to move among different user accounts to access my content. Hence, this is an intermediate step.
3) Once the content has been transferred and I am certain it is available, I erased the content of the external drive and moved the content from the second account back to the external drive. The content is no longer in the format required by Time Capsule (which is a good thing) and individual files can be accessed. You might want to use a second hard drive if erasing the originals make you uncomfortable.
4) At this point, I can connect to my original user account and integrate the files I want. I can move music into music, pictures into pictures, and documents into documents.
5) When I am certain I have what I want where I want it, I can delete the temporary user account using Apple preferences. This frees up space on my computer.
6) Finally, I can use Time Capsule if create new backup of the contents of the new machine on the external drive.
I have used this process one time. Because the way I use technology has changed (I am now mostly working in the cloud) and technology has changed (Apple allows me to download applications I own to the same machine or different machines multiple times), it is unlikely I will use it again. However, it worked for the situation I encountered and may fix a situation others encounter. If you are careful when moving from step to stop, there should always be a backup should you make an error and need to try again.
