(1) the big problem I am having (other than time/money and motivation) is when I ground the 273 rockers on the valve grinder the face is at a slight angle (& I mean side to side/not correct), not the normal "arc" they have from the pivoting on the grinder when done correctly and the way the rocker sweep over the valve tip. I could only get the apparatus to work (antique Sioux 622N) by grinding it on the side of the wheel. I trued the wheel and the pivoting holder is secure/appears to be level & the rocker appears to be vertical in between the two convex "cones" that secure it but something ain't right. Earlier I was able to get it to grind on the front of the stone but the rocker was way above the center line of the stone "horizontal" plane & that was even worse. What am I missing! EDIT (2)I have 5/16 clearance, maybe a hair or two less when it all compresses