This Switch had flickering Link and Act LED's and no LED self test when first switched on. I took the case apart by removing 4 screws from the top of the case and 3 screws from the bottom front of the case. I found one bulging 1000uF 6.3V capacitor C67. I removed C67 and C68 and tested them with the ESR meter see photos below, both had problems one was open circuit and the other was low in value and high ESR. I replaced them with High Temperature Low ESR Capacitors. After replacement the switch went through a proper self-test with the LED's switching sequentially etc when powered up.
It was working fine after this, however the fans also needed replacement as well because one was seized and the other very noisy. I gave it an extended test for a time and it showed no signs of failure so not bad for a quick look inside the case and some soldering.
The bulging capacitor is a common fault in electronic equipment so it pays to examine all electrolytic capacitors on faulty equipment.