A bit of thread drift but issues often seems to be missing in conversion training from fixed to VP props
1) a bad prop seal will allow oil/grease to escape. It will typically be a thread extending outwards from the hub on the inside of the blade. If you see this have an engineer look at the prop. Certain props have the hub oil dyed red. If you see any red stains on or near the prop hub, the hub is cracked and is unsafe
2) The point of cycling the prop is 2 fold. First to circulate cold engine oil out of the governor and prop and second to check the governor operation. 2 cycles is plenty and you should only let the RPM drop 200 to 300 hundred RPM. Very low RPM at runup RPM is hard on the engine
3j if the prop RPM starts hunting in cruise the first thing you should check is engine oil pressure as low oil pressure will affect governor operations
4) if the prop runs away it has probably gone to the fine pitch stops which means it is a fixed pitch prop with a very fine pitch, if possible enter an aggressive climb to slow down as for most light airplanes the maximum airspeed that won’t over speed the engine will be less than 100 kts.