Thats the thing, in terms of SEE, you don't slave it to another drive for recovery. The articles I linked specify booting from the recovery CD/USB while the encrypted drive is still in it's original chassis (or another of the same make and model, if possible), and running through the recovery options there.
As you're booting from the recovery CD, you should avoid any boot record issues on the encrypted drive. Obviously if the drive is suffering a mechanical failure, then it's going to be pot luck as to how much can be decrypted. Perhaps take a RAW image of the disk, and try decrypting that instead.
In this sort of situation though, I'd highly recommend contacting Symantec support to see what aid they can provide.