Beomaster 2400 no mids. Any suggestions?

So I purchased a Beomaster 2400 along with a Beogram  4004 player and Beovox s45 speakers. I noticed the sound was very off, even playing from an mp3 source, so I got a 6.25mm to 3.5mm adapter, ran the sound to my earphones and it seems like the problem lies in the amplifier. Music sounds pretty "blown out", even in new earphones, and there seems to be no mid-frequencies at all.

I'd like to try and repair the amp myself, because it might be a fun project. Any suggestions on where to start fixing it?

These are getting old, so it could be a capacitor problem. When you move the treble and bass slider pots, does it change the sound? Do these pots seems to move too easily? If you can't ear a sound difference, it could also simply be that one of these pots as failed.

Guillaume

You can get a capacitor kit with instructions from Martin (Dillen on site). Message him and he will get in touch. Not the easiest receiver to start with!