Over the past few years, I have taken apart a half dozen GP7/GP9's, a 2321 FM unit, a New Haven Rectifier, a Virginian Rectifier, and a New-In-Box Green 2340 GG1. All of these have been in our family for 50 to 60 years. All of these have the vertical motor with dual thrust bearings and they all have something else in common...
...the upper thrust bearing for the armature has no sign of ever having been lubricated by the factory. Lionel Lubricant (usually in a state somewhere between gummed up and petrified) is always present on the lower bearing, but never in the top one.
Has anyone else seen this?