Transmission Main Drive Gear A-7017

[Ed in Maine]

I am installing the transmission and find that the pilot bearing just slips on the shaft. While the bearing isn't sloppy on the shaft you can turn the inner race on the shaft. There is no interference fit. Are there any tricks to shim up the shaft just a bit so the pilot bearing is snug or is this shaft toast? Driving the car last summer, there was no problem with the transmission. Thanks for your help. Ed