Single letter Capacitor Code?

I have two surface mount devices that look like capacitors but I'm not sure of their value. Both are a light colour, one with a slight green tint and the other a bit yellowish. The one has a red "R" and the other a black "A". There are no other markings. A quick in circuit test gives me the impression that they are capacitors. I don't have an ESR meter. I've tried to remove the one that I think is a problem but it is epoxied in as well. I don't want to crush it until I know what it is.

Any help would be appreciated.

That sounds unusual!

Photos would help, especially showing where in the PCB they are which might help determine if they are caps or other devices.

The device is an attenuator out of a tektronix ossilloscope. Here is a pic.
I tried to zoom in as best I could. The component is near the top of the pic near the metal loop.

They look to be custom markings.

The easiest way to identify would be to remove the parts and test it.

If they are SMD ceramic caps its unlikely they are damaged, most failures are components that carry significant heat/current, or parts that dry out over time like electro caps.