If you have any other word processing software on that venerable iMac, you could try opening your file with it.
SimpleText or Word would be worth a try.
If either of those two actually open it, it will not be pretty but all you need to recover is the actual text, not the formatting.
P
Greetings: I have a new-ish iMac and a very old one, OS 9.2. I use the latter for typing manuscripts and it is fine for that. I'm used to it and it's worked very well. However, lately it's making all sorts of clicking sounds and has gotten awfully slow. Today I spent all day typing and saving as I went along. But when I closed the file, I discovered I couldn't get back into it (Appleworks). I got a message saying it is "corrupted." I've tried everything to open it; disk repair, etc. but no luck. Before I give up on a day's work, can anyone offer any suggestions? Many thanks in advance.

Chowhound
Comic Vine
GameFAQs
GameSpot
Giant Bomb
TechRepublic