Read carefully, and absorb each instruction before doing it - anything which can break, will.....
Underneath the BM1600 are 4 bolts - unscrew them.
Then, pull the Tuning Knob off, firmly.
Then, GENTLY pry the dial-glass (actually acrylic) faceplate out and away from the receiver body. Notice that it is suspended and held by 2 black plastic clips below and at either side. These break easily - be careful. I had to rebuild mine from plastic card!!!!
Then, behind the now released faceplate, identify the 2 HIGHEST screws. Release these 2 only, and leave the other screws alone!
Then pull the Wooden Casing to the rear.
Now, you've exposed the guts of the receiver.
Follow the black wires to the indicator lamp housings. The bulbs should simply pull out with a tug on the wires, barring any heat or other damage (or non-professional repair jobs).
Good luck!
Menahem
Learn from the mistakes of others - you'll not live long enough to make them all yourself!