Probably easier to rewrite it from scratch. Disassembly is a pig of a job.
Oink, oink - I agree.

On one occasion (factory burned, nobody had offsite copies) I was tasked with a similar job. I did disassembly and fought it for a couple of weeks before realizing "this is more trouble than it is worth" and startong from scratch.

If you want to repeat that mistake, there are disassemblers out there (search here and you will find a few links) Craig has a good one, click his ad above.

Erik