There were three issues with the early 1800 Wings. One being the cracking frame, one being overheating problem, and the other being the alternator drive gear.
I'd heard that none of the Canadian models had the frame cracking problem but I can't verify that, it's easy to determine if it does or did and has been fixed. Also, I think it was only '01 - '04 that had this issue and not all of them. Apparently Honda changed the frame design in late '04 to address it. There were also overheating issues on those same years. Again, not all of them. It was a factory recall for both problems.
Here's a link to some info on this... 01-04 1800-What to look for. - Honda Goldwing Forums
As for the alternator drive gear, they were prone to failure and the motor has to come out to fix it. A real PITA. My Wing had that problem and that's why I got rid of it otherwise I might still be riding it as I put a LOT of work into customizing that thing. You can tell if it's bad coz they produce a loud whine or rattle. Sometimes it's the alternator itself which is an easy fix but generally it's the drive gear.
I think they rectified that in the '06 model and up.