I have been in the same boat you are in, in terms of getting older spare parts. And I have learned that sometimes you have to buy the wrong things, to find out what the right things are.
I personally went through about 15 seperate din connectors until I found the 'right' one to use with the Sega V2. Or at least one that ended up working anyway.
Needless to say, since the Sega came out, parts and components have changed, part numbers are different, and even suppliers have changed or gone out of business.
The coolest part of the process for me has been learning. And also to report back what I have learned or found out back to the forums.
-just my 2 cents... feel free to give me change if you want.