Let me help you here.....
Your Model 541, made between 1923-1925 is a one that has NOT been factory rebuilt, just serviced by a service center at one point. Those of which you have seen that state "previously Reconstructed At Factory" are one that were traded into Hoover dealers, sent to be completely rebuilt, and cosmetically spruced up (often the metal finish was panted with what ever current models color), then resold as the budget option.
Your 541, as far as the body and handle, paint, motor, badge, and metal finish is original. However your bag is a genuine Hoover replacement, and the Model 541 would have originally had a cloth covered cord. So that would explain the Service date of 1939, that's what that is, dealers and vacuum cleaner shops alike tended to make a reference date to the last time it was serviced. Sometimes, you will some machines with several dates stamped all over the bottom, indicating that it was serviced, and or repaired fairly often.
I am including a picture of what a all Original 541 should look like.
