The 241, 242, 251, 252 &amp; 253 used the same bearing. Should be a 1 3/16” round bearing. Your local bearing distibutor can get them for you. Lots of online stores sell them. They range in price depending on manufacturer from $12 - $40 and where you buy them. W208PPB7, DS208TT7, 1AC081.3/16 DISC HARROW BEARING is the description/part number you need. I'd get some spares if I were you.

The museum would be one place to buy manuals.  call (641) 228-1099