I had a brand new Melling HV pump seize while priming the engine with a drill. While I had taken great care to pre-lube the rotors and pack the cavities with Vaseline I hadn't thought to lube the inner rotor shaft.

I had never pre-lubed a rotor shaft on many previous builds and never had a problem (I thought) but a dry rotor shaft might cause some minor galling that doesn't appear as a problem until later.