I have an early '90s Busy Bee DG1224g and was able to get the manual from Busy Bee electronically. It's been working great for me but that depends on the previous service it was exposed to, your experience may vary. The previous owner of mine said it was lightly used.
If you can pick it up for a good price and it's in decent shape, give it a shot. And although it says Busy Bee Canada (British Columbia) on it, I think they still came from Taiwan. I'll double check my marker plate when I get home.