I'm a fan of the bolt-in button too. Wrecked and lost a push-in bronze button in 30 seconds . . . loose hole in the clutch release arm. it is also critical to have the button centered on the PTO center button, and to have the center button centered in the PTO. The early PTO style with the curved tips on the spring located the center button precisely; the flat double springs can wander based on anything that happens. I've lost quite a few bronze buttons and center buttons because of that, also the three small clutch release springs that go on the bolts were soft (1-1.5mm shorter than new), and that also seems to influence things. Make sure you remove all side-to-side play in the clutch release arm, so that it can't move off-center on the PTO center button. I'm ruminating on how I can "locate" the center button so that the clutch fingers don't slip off the edge of the groove in the center button . . .