The power cord has 3 ends on it. 1 goes to the receiver and the other 2 go to each speaker. I don't have a manual with this.Can you give me a general idea of how to remove the door glass? thanks

I recently bought a nice beosystem 2500. It was made in 1991. I paid $185 USD but the 3 ended power cord was missing. I had to get the cord from B&O in NYC. They charged me almost $70 USD for a freakin power cord. Everything works great except the doors don't open all the time. I'll wave my hand in front of the doors over and over but they