Crucial functions not available

In the compatibility query my cassette deck was listed, which I want to control it.
Nevertheless crucial functions of the original remote control are not available.
But I now have rather unimportant functions are available, which does not offer the original remote control.
Because I do not have the original remote control, I can not teach subsequently also the important functions.

Too bad, because the standard functions I could operate with a 10 EUR universal remote code programming so far already.
So when it comes to get more than the usual basic functions of simple universal remote controls, one is not better served with this remote control.

Now I have to again spend significantly more money to bid on a very rare cars original remote control, as new, there's the long gone - or has anyone an affordable Sony RM-J801?.