I think you need to really look at your system before you get it or put it back together yourself...
I think that it leaked out the R12... and that your backup systems which should have protected the compressor failed to operate correctly...
Thus you lost the compressor instead of just the R12...
Some compressors have a supreheat switch on them... plus the high/low pressure switch on the R/D....
I would SURE hate for you to lose a NEW compressor due to your backups failing again.... A really sickening thought...