Hi Kai,
Welcome to this beautiful forum!
APLD stands for advanced program locate device.
I am an old (~57) and aged member here but there are much more smarter and intelligent folks here.
basically once you turn the APLD on and select a number like #3 on the buttons and press play and FWD simultaneously it will scan and find the 3rd song on the tape from the place you started. If you begin from start it will pick the 3rd song.
If there is no sufficient audio signal gap this function might not work. There must be a certain amount of "no signal part" between songs.
So professionally recorded cassettes should work well.
Beat cut?
See think link...
http://www.stereo2go.com/topic/what-means-beat-cut-
The frequency of the bias signal applied to the tape during recording of AM broadcasts interfers with the received signal and causes noise. The switch reduces or eliminates this effect. Most bbx models offer at least some form of beat cancel, (with the exception of the most basic), and many offer two or three position switches for this purpose.
1. BC Beat Cancel
2. BC Beat Cut
3. Beat Program (Position 1, 2)
4. BFC Beat Frequency Cancel
5. BFO Beat Frequency Oscillator
6. OSC Oscillator Control
7. RIF Radio Interference Filter
8. BP Beat Proof Function
Regardless of what it's called, (see a.k.a. list) they all perform the same function.