Casper's VSS adapter help needed!

[YGETV8]

I'm new to hybrids having just bought my RX7 3 weeks ago from Ted on here. Got to doing some datalogging and saw that while the Mazda speedo reads just fine, the ECM thinks it is going much slower than it really is. Ted had said the converter lock-up wasn't working, and I'm pretty sure this could explain why! Is there an adjustment that needs to be done? If I mess with it, will I screw up the speedometer reading?

Thanks, Jay