You've got the right movie. It's either a piano or an organ, I can't remember which, but it's owned by the grandparents, Jason Robard and Eva Marie Saint, and it plays a very big role in the climax of the movie. Unfortunately, I can't find this movie anywhere. It was made for TV, but it's one of my favorite Christmas movies, and I can only hope that someday they will realize why it should be redistributed.
I saw this movie a long,long time ago. It may have been thirty years ago. Jason Robards became one of my favorite actors. Each holiday season from Thanksgiving until Christmas I keep this movie in mind hoping it will be shown on television again. I have never seen it again after all these years. I named my youngest son Jason, thinking of this actor. I will begin looking for this movie as a DVD,now that I know the title. As I recall, it was brought to the TV screen by Hallmark cards as the sponsor.
I, too, have been a long time fan of this movie. I taped it the second year that it was on TV and then later found a DVD of it which turned out to be a DVD of a taped version, I think. Either way, I watch it almost every Christmas season. Jason Robards and Eva Marie Saint were just superb.
One of my favorite scenes is where Jason Robards has Rusty get Eva Marie Saint drunk so that she doesn't know they are moving the organ. He tells Rusty of the four stages of inebriation: jocose, lachrymose, bellicose and comatose. His job is to get her to the comatose stage.
I too taped the film - one of those winters long long ago when Time Warner was having its usual broadcast issues and the reception was dismal - but the tape still exists. Little did I realize all those years ago that I would one day be able to digitize my only recording of the film (since the PTB seem to have forgotten its existence and it hasn't appeared for many many years.)The TV quality is (more than) terrible, the sound is not that great, the color seems to have diminished, but the story is just as moving and magical as I remember.
"No fate but what we make." -Terminator II