Without understanding the internals of it I would guess very difficult to do - given the age of the machine then very, very difficult to do.
Motors on 50Hz may run a little slower and it would take loads-a-money to make your own 60Hz supply - I think the transformer solution is probably the most realistic approach.
Are there any heaters in the thing? Another major issue for you if you attempt to convert it.
Good luck...
Peccavi
May 2010