It certainly would help if you could provide some more info on this. If I remember AIX 4 uses JFS1. There are some software solutions that can handle JFS. However JFS1 is not the same as JFS for Linux. And if you have a RAID set then it certainly would make things even more fun
Depending on what the problem is, using another AIX box to mount the FS would be a possible option. If that does not work, send it to a pro. If you are a pro, then outsource to a shop that has experience with AIX.