VPI TNT Owners

I need some advice please, I own the TNT 3.5 and I just
bought a new armboard for it. I am trying to set it in it's slot but seems real tight , I can't get it to seat properly, any suggestions?

Thank you
A standard TNT armboard is 3 15/16" x 10 15/16". Is yours different?
I just got off the phone with Mike at VPI and he tells me
that the actual corners might be off ever so slightly.
He told me to sand the corners.

Thank you