Conrad-Johnson Discolored (rusty?) Allen screws on side of MF-2550.

They are just oxide finished hex cap screws, they tend to rust. You can unscrew them and use WD40 and a toothbrush to remove surface rust. 

Thanks for your help.

my first step is to have the factory do a serious inspection and replacement of any part(s) which is needed.  

    Congrats on the new CJ power amp, they are a great company. Enjoy.

 What speakers and other components are you using..



   

Speakers are NHT 2.5
Preamp is McCormack Micro Line Drive
DAC is Jolida FX Glass DAC III
CD Player is Rega Planet
Turntable is Thorens TD-203
Phono Stage is Rotel RQ-970BX
DVD and Hi-Res: Sony UBP-X700

Not real high end, but I used the system for many years with a smaller amp than I just got. I’m a little reluctant to spend a lot for a factory check when everything is working well but I may ask them how to handle the rusty screws.

Those appear to be socket head cap screws that are often made from black oxide alloy steel.   The black oxide process is used to add,

"mild corrosion resistance, for appearance, and to minimize light reflection. To achieve maximal corrosion resistance the black oxide must be impregnated with oil or wax."

Moisture in the air (humidity) can contribute to corrosion.  Humidity present in lower levels of conventional homes (i.e., in basements) can condense on cooler surfaces.  Increasing air flow, increasing temperature, and operating a dehumidifier all help reduce problems related to humidity and condensation.  However, even mild condensation over years could have contributed to the oxidation you see, it is not uncommon on those types of screws.

If you are concerned, open the top and look for any obvious evidence of corrosion inside (be safe - unplug the amp first and do not touch any large capacitors or other areas which could result in shock).  If you see significant evidence of corrosion inside, take a picture and send it to CJ for discussion. However, if everything looks fine then I wouldn't worry about it except to make sure you are operating the amplifier in a warm, dry place.   If you wish, you can replace the screws or clean and oil them as discussed by @russ69.