Got a question about a 489 suregrip that I just picked up.

If the thrust buttons are missing it is difficult to press them in without disassembling the center section. You would have to support the thrust spacer, within the differential, as you press in the 2 thrust buttons. It's much safer and not that difficult to install the buttons with the center section apart. IMO.

Talk to this guy, I'm sure he's got extra buttons. http://www.doctordiff.com/