faulty melos 222 help please

I have a melos 222 preamp A or B that has noise and RF interference problem and I have only a diagram for C version.I paid melos a lot of money to fix it ,they took my money but did not fix it.They cannot provide a full diagram and their PR guy Sedrick Harris is a waste of time.Any help appreciated.
My first suspicion would be the tube(s), but I assume you have already tried various tubes. As far as I know, Melos preamps operate in balanced mode internally, so it is not picking up RF internally. The RF might be leaking in to the input wires that run from the input rca's to the board itself. Any interference picked up here would of course be amplified. The RF might be local to you, which would explain perhaps why Melos did not find it or fix it. You might try ferrite rf blockers, either on the interconnects or the power cord, and if that doesn't help, then perhaps a torroidal choke on the internal wires (if you know what you are doing). OR, perhaps the internal wires are UN-shielded, like most preamps, in which case maybe replace them with ground shieled wires? Please try any of these at your own risk, keeping in mind that tube components can have lethal voltages in them, even when unplugged!
We have not had goodluck with Melos & reliability. We will know longer accept them as trade-ins. They do sound good.... thanks, Brian@HelloHiFi.com ph805.527.9739 fax805.527.9808 www.hellohifi.com eCatalog available. New equipment demo’s by appointment. All quotes are good for 30 days. Customers in every state, & 26 countries (angol/ingles/englisch/beszelunk magyarul!/ hablamos en espanol/wir sprechen deutsch).
I have a Melos 222, and I have a very slight problem with extraneous noise. However, I am using a power line filter, and that seems to help. By the way, can you help with an instruction manual for this. I have been trying to get one from melos, but they have ignored every email I have sent to them. What I need most is how to set the loading and gain for the phono stages. Also, if you have any disgram on how the cables should connect for balanced mode, i.e. twin RCA's to Balanced cable, that would be very helpful also. Good luck with your preamp. From what I am seeing on the site, very few people want to have anything to do with it. But it still sounds good, so i guess we'll just have to live with it.