My dad and I installed a Toto Drake. He's much more of a plumber (and overall DIY'er) than I am. Most of the installation went well, but the tank wobbles in the front/back direction.

The instructions say to make sure the tank makes three points of contact with the bowl: front left, front right, and rear. It's the rear spot that's not making contact, hence the wobble.

I fiddled with it to try to get all 3 to make contact, but I couldn't. Any suggestions? Will this pose a problem functionally at some point?

The toilet seems to be working fine; no leaks.