I have a CA 2000, a AU666 (running as the amp with the CA 2000) and a TU666. All are running on their original capacitors will no problems.
The components are all very high quality with a long life. I firmly believe in leaving these devices alone. If it sounds good it is good. If it started to sound crappy and it was not switch related. I would have it serviced. The one issue I have experienced is noisy switches and rotary dials. These are tricky to clean, as it is hard to access these without completely removing them. On the whole, modern quality audio components benefit from all the technical advances made since the 70's. Still I use these because I love the sound and the look. The same reason why I run an old Sony 557ESD CD player. Looks and quality.
The components are all very high quality with a long life. I firmly believe in leaving these devices alone. If it sounds good it is good. If it started to sound crappy and it was not switch related. I would have it serviced. The one issue I have experienced is noisy switches and rotary dials. These are tricky to clean, as it is hard to access these without completely removing them. On the whole, modern quality audio components benefit from all the technical advances made since the 70's. Still I use these because I love the sound and the look. The same reason why I run an old Sony 557ESD CD player. Looks and quality.