[Roadsters] 5 speed transmission help

[toolmansj2 at comcast.net]

I currently have my 5 speed completly apart to install new bearings 2 things came to mind!

1. How can I tell if the syncros are worn out or need to be replaced? I dont want to just buy new ones just because, they are not cheap. This tranny is a borg warner type with brass syncros out of a late 69 model. 

2. What part of the 5th gear should be welded I cant see anything that would break loose. I dont have a bad one to compare to.

Any help with these questions will be appreciated
Thanks Shaun Tracy Ca