Last week found a 500A (1961) in a wonderful desk for $25.00. Machine is pretty gummed up with some white stuff on the gears. Serial #172503. Is this a Rocketeer? I didn't buy it at the time and am so afraid it won't be there when I go back. Have a 401A, 185J, FW centennial, Kenmore model 158.14300, Bernina Deco 330 and a plastic Singer (ugh!) Seems I have become a vintage snob. If it is there, what is your opinion on adding this to my babies?