This is becoming very silly.
The matte doesn't match the set or the model.
He can't be thrown down the lift shaft Luke and Vader travelled up because the lift is clearly some distance away and as there is no other lift around it's doubtful it's a lift shaft at all.
It can't be the main reactor because that is way too far away.
He falls to his death and explodes down a chasm in the centre of the tower to the side of the lift shaft.
There may be a reactor somewhere down there but as we don't see it does it matter?
The one thing that is clear is the matte needs to be changed and possibly the model too.
As much as Jedi has some fine effects work much of it is kludged in this manner and getting hot under the collar about it serves no purpose.
Hopefully someone will one day reach a successful adjustment that can make sense of the mess.