This is the primary power supply board in the 2500 master station. The red arrows point to the 5 primary capacitors on the board. After 40 years these all need to be replaced. The 2 large black capacitors and the 2 small orange capacitors wil not be a problem to replace with modern components. The large silver "can" capacitors will be a challenge to replace, it contains 4 capacitors inside the can. This type of part in no longer available to buy. Space inside the 2500 will be the biggest obstacle when replacing this part.