Hello i have a chance to pick one of these up, but its missing one of the chronograph pushers how much would it take to replace it? I see some pushers on ebay go for a little under 100 are all the speedmaster 3510 the same size pushers? Is it something i could replace myself? ill add some pictures let me know what you guys think and advice and if you guys have some price ranges on how much i should spend on the watch and how much the repair would be that would be great!