Did you find the leaks from the cap? Is there any damage on the circuit board? Too bad you're in England or I will have you to upgrade my 6K's
Sometimes they can leak or bulge at the top cap. But sometimes they can completely fail with no physical signs. Even when they have failed and still in circuit they are difficult to find by measuring.
I would say you may even be unlucky to have a problem at 15 years old. A 5k I was just working on was probably 15 years old and the caps were in a bad way.
I would have done whatever I could to help you but Marc is highly experienced and I'm sure would do a great job just like I would do
