Pilot/spigot bearing holder

Need some advice from GTD types. I am assembling my transaxle to the engine now and do not have a spec on how much the transaxle, an R-21, input shaft should engage the pilot bearing adapter that is inset into the back of the crankshaft. It appears to be a balancing act of sorts, looks like if I push it all the way in, I get no engagement, but if I don't press it in deep enough, the bearing holder could fall out. Is this supposed to be set in for a measured amount of engagement, for example 10 to 15mm? Any thoughts?

Brian, Idid an article in an earlier GTDclub magazine on how to measure and set the spigot bearing and carrier. If you do not have it I will post to you, Frank