I have used a CJ premier 14 for fourteen years with no maintenance other than tube replacement every two to four years. The only contact cleaning is with a rough cloth or br turning the RCA connectors a few turns. Sounds as good as new. Ed in the service dept can be very helpful. Thet are this week, but try them in the new year.
Maintenance for Tube Preamps
I've enjoyed my Conrad Johnson tube preamp for a decade or so. Other than replacing the tubes a few times over the years there hasn't been anything else done to it. Are there other maintenance tasks that I should attend to? I believe all the capacitors are polypropylene (no pesky electrolytics!). All seems well, but I want to make sure I'm treating it properly.