Has anybody replaced their vacuum pump? Mine is getting noisy (marble rattling sound) It doesn't look that bad from what I can see in the videos. Is the special holder to keep the sprocket from turning really needed? Looks like the chain drives the oil pump and vacuum pump so timing is not an issue? or is there a balance shaft involved? tensioner is a simple spring loaded and doesn't lock and there is actually a little holder tray to hold the vacuum pump gear while the pump is out. All sounds pretty doable even without any special tools or am I missing something?? The tool kit shown in one of the videos (N54) looks pretty good and I wouldn't mind spending $200 ish if it makes the job easier but looks like it's no longer available. Does the N52 need different tools than the N54?