I know you're going to hate to hear this, but you could have ordered the entire folding blade conversion from my shop (helitek-rc.com) for $4 less than you paid for his AND we include a free set of hardened blades with our kit instead of the cheap ebay blades he includes with his.

The work around to your problem is to replace the top part of your swashplate with the top part of an Esky swashplate, then use the Esky links from an Esky lower rotor head.

Unfortunately in order to do that you'll wind up paying for a swashplate and lower rotor hub, which will probably run your $12. The lower hub has nothing to do with the size of the swashplate balls or the size of the balls on the blade grips. If you did get his lower rotor hub, he'd then probably try and sell you his links, which is what you'd actually need to fix the issue using his parts.