Problem with fastlane diff cups

[maxxdude1234]

just got my fastlane diff cups, ripped the packaging open...and....they don't work properly. The 2 slots that the spyder gear shaft is supossed to run down are too close together and the little spyder gear shaft won't fit in the cup. Looking back at the stock cups, they have a square slot, but the fastlane cups have a circualr slots - which means the spyder shaft (which has a square end) cannot fit in. I've tried filing the end of the spyder gear shaft down, but it's chrome plated - and I don't have anything hard enough to file down chrome....:W:

Wondered if anyone else has had the same problem, and how they solved it.

ps. if you need pics to understand what I'm talking about, just ask...Thanks :)