RTJ400 box joints

I used my jig for the very first time to make two serving trays with 3/8" box joints. On all 8 joints, the pins are 1/16" off the tails. Why? It is consistent, so I don't think I am doing anything sloppy; but am I doing something wrong?

I can fix it with the jointer, but for that price I shouldn't have to.

I've only used my RTJ400 for dovetails but that problem (if I'm understanding it) is solved with bit height adjustment & with that I can perfectly flush tails & pins.

I don't have this jig, but I have other Leigh products. Read the manual and I believe you will find that the problem is fixed by adjusting the eBushing which loosens and tightens the box joints. If the pins are proud of the matching piece, then the issue is likely a depth adjustment with your router bit.