I have a very rough Arco frame.
It's a model 4921.
I have seen models of 25xx,36xx,etc but no other 4921 and like most of us with new old toys,
I'm curious about it.
I did see a thread that said on the 25xx models the 25 stood for 2.5hp and the last digit might be the year.
Anybody have any Arco...