Can anyone help me locate a 5/8-18 arbor nut for a Ryobi BT3000 table saw? I was changing out the blade on my 25 year old saw and the nut cracked in half. Apparently a standard 5/8-18 nut doesn't work because I can't get it to turn past the first thread on the spindle. The saw still works well and I would hate to have to drop $600 on a new saw just because I can't get an arbor nut for this one. Would appreciate any help.