Yes you're right. Strobe markings on the platter is 50hz (someone told me that the 401 was a uk domestic model only). I actually had a power supply made to make it work at 50hz but it blew up so for the meantime i'm using a 60hz pulley which a friend helped me get thru ebay. Had to get the pulley twice as the first one that came was a bit wobbly. It just won't play music at the right speed if you use the 50hz pulley.
I hope everything turns out fine with your 401.
I hope everything turns out fine with your 401.