If this is a live customer switch, then you need to bring in an experienced, trained tech. There is potential here to lose the database.
If you chose to ignore my warning and act alone, you can try to activate the HD controller 1 partition E by using:
ACT-DSSM
I do not recall the exact order of the parameters, so I'll wing it by saying "controller/CNO =1", partition/ANO = E, unixboot = no, then type semi-colon.
Use DIS-DDSM:A1 to status that partition for a while. If it stays up (in service) and all the other partitions on that HD controller 1 remain in service, then you will have to reload the system from controller 1 for it to become the "Active Load Device". This means the system will be DOWN, aka NO DIAL TONE, and since the hard drive may be bad, it means that the system MAY NOT COME BACK UP!!!!! But if you feel lucky, the command is:
EXE-REST:SYSTEM,RELOAD,STD;
You must type the "STD" or the system will boot from the lastload device, which you say is controller 6.
If system will not load from controller 1, then you are in trouble. I cannot stay on this site all day to assist you with attempting to boot from GLA or controller 6.
This is why I suggest that you find an experienced tech to resolve the problem.
Good luck! Please re-post and let us know what happens.