Creepy Episode (help me identify it!)

When I was around...oh, who knows, but young...there was this episode of Mr. Rogers that totally creeped me out. I've been trying to identify it for a while (using Google and such), but with no luck. I know there are hundreds of episodes, but maybe one of you guys will remember this.

So I vaguely remember the crew in puppet land talking about "someone coming". I just recall that the puppets and company were expecting someone (I may be remembering this all wrong, though, so ignore it if it doesn't spark a memory).

The part I do clearly remember was when it arrived.

The characters look up into the skies of the puppet kingdom and see a chair floating down from far above. Glowing lights are attached to this odd looking chair (they may have been blinking). In the descending chair is a figure, a humanoid puppet, but my images of him are pretty vague.

The smallish figure and chair kept descending are the creepiest music played (which I think contributed to my fear). He may or may not have been making odd sounds. I don't remember anything else, I may have turned the TV off.

Again, some of these details may be incorrect, but I know I have the general idea right.

Anyone remember?