Definitely don't try anything with at least a couple of backup db's, and I would have at least one on some other media such as a stick or cd-r. It's not hard to think you're in one copy only to find you've just messed with a backup. Tend to agree with 'if it ain't broke' thing, unless it's causing issues, and you'd have to weigh those against the prospect of redesigning it. If you don't find a suitable freeware or open source tool and can't get approval to purchase, you'll have to be good at searching and adapting code, and it will take time.
I started to write procedures to find all traces of keywords in things like sql; can't recall exactly where I left off. Had it working to the point where it would find a phrase or keyword in any query or control rowsource, then moved on to looking at tables. I dropped it because it became apparent that the potential paid job where I would use it didn't pan out. It will be a big task if you take it on yourself.
The more we hear silence, the more we begin to think about our value in this universe.
Paraphrase of Professor Brian Cox.