Good news is that it's a 23-channel radio, not a 40.
Bad news is that it's 45-plus years old.
If it was a car that age you would be shopping for every gasket, seal, hose and belt it has.
Just to start.
Access to a tube tester can save a lot of time. The tube sockets tend to wear out in that radio. If you can feel a decent amount of friction when inserting or removing a tube, this is a good sign. A tube that wiggles about loose in the tube socket is trouble. The quality of connection to the tube's pins will come and go. That socket has to go.
A surprising part of the trouble you'll see is from dust, dirt and oxidation on metal-to-metal contact surfaces. Controls, switches, circuit-board plug-in pins, tube sockets and the pins on the tubes all need to be free of any schmoo layer.
The relay bears checking. Easiest test is to tap on the top of it with the radio on the antenna receiving noise or channel chatter. Tapping on the top of the relay should not cause scratch noises. Tapping on the side, as in the side facing the left or right will always produce some 'pop' sound, but not tapping on the top.
Just one problem with this test. Every, single tube socket must be free of scratchy noises first, or you'll hear tube-socket noise when tapping the relay. Crackle noises from tapping the relay only mean anything if you can tap on the surrounding tubes without any noises.
There are three plug-in circuit boards. The header pins where they connect get scrubbed with solvent and a cotton swab until the swab comes away without being darkened. A squirt of solvent into the socket as you plug it in usually cleans up the spring contacts okay. The silver-plated contacts on the channel selector need to have the black tarnish washed off, and a proper "control" cleaner with a light lubricant used to reduce wear on the rotating contact surfaces. A surprising fraction of the faults this model shows you are mechanical in nature.
A list of resistors that need to be changed is around here somewhere. Mileage is a factor. No odometer, but the appearance of 2-Watt carbon resistors on the circuit boards is a clue. Bubbly surface texture, faded color bands indicate high mileage and the odds of a resistor that should be upgraded to the next size up. 2 Watt becomes a 5-Watt, 1-Watt to 2-Watt, and a couple of half-Watt parts get upgraded to 1- or 2-Watt parts.
The electrolytic capacitors must **ALL** go. All of them. No exceptions. The high operating temperature in a D201 prevents them from being reliable at this age. It has a lot of them.
And if the plug-in "BA" board is dark and burned-looking we sell an upgraded replacement on fleabay.
And if it isn't, this suggests low mileage.
Low mileage always works in your favor. High mileage does not.
73