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.
bama214
Thanks to all who responded - good advice! A bit of contact cleaning is probably a worthwhile thing to do.
I would stay away from Cramolin. It does tend to keep cleaning even when you don't want it to and can leave crud behind. I use pro gold but again if it isn't broke don't fix it. Changes can be made sonically to the preamp by replacing coupling caps etc.
By the way, I mentioned Cramolin but haven't used it for at least a decade. Cramolin violates some EPA regulations and was not rated as safe for plastics. Cramolin is no longer readily available, and I only mentioned it in case you happen to have some lying around. The Caig Deoxit Gold 5% solution/Pro Gold are much better. Interestingly, you cannot legally ship Deoxit/Pro Gold through the air - it must travel by ground. And if you order more than one can, it must travel in a separate package. I think this only applies to the aerosol version.

Anyway, the point is if you already have a can of Cramolin lying around, go ahead and use it, but sparingly, wiping off any excess with a lint-free cloth. Since you probably don't have it, order a can of Deoxit Gold 5%. You can find it any number of places online if it's not carried in your area. Musician's Friend had a good deal on it recently, and you can definitely find it on Amazon.
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.