There is one thing that gives me pause for thought in looking at the photo of the steam chest with the missing stud at 4 o'clock. It looks like the jam nuts are cinched down tight on the slide valve flange, and if so, then the slide valve can't "float" over the ports using the steam pressure to seat it against the port face. If in fact the slide valve can "wiggle" and is not held rigid by the jam nuts, then all is as it should be, but if there is no wiggle room available and it is clamped tight as it looks in the photo, then I don't think that is right. It needs to be able to move free, not much, but enough so that it can find its own seat against the port face when under steam pressure.