My two old Standards have the OLD firing system (the pointed metal bar on the firing switch that you had to file periodically and noalox. They need the button tops to work reliably. I CAN make them work with flat tops but they will suddenly decide not to make the connection as I found out 70 miles from home on a shopping trip to the big city.Do only the oldest REOs need button tops? I use flat tops just fine in my Grand LP, Mini 2.1 LP and P67.
@Spydro would know
If you have the new firing system with the curled gold bar on the firing switch flat tops are no problem.