Great find on the ESP selfpropelled machines. Yes, back in the day when Eurkea introduced them (blue first '79) They quickly learned the need for the ribbed wheels. I never changed any in my shop during the mid 80's. I did sell several of them during that time. There were a lot of them
sold in the columbus/Dayton Ohio area. I think I have only
seen one in a thirft store or flea market!
Norm