Hello!
Recently bought a used RB800 and saw the damaged element on the board (possibly a capacitor). In general, the board is working, but would like to find out the nominal value element for its future replacement.
A damaged element likely screwing the mounting nut - mounting hole very close to the elements.

After talking with the support received the following information:

It is: C418 - 100nF 16V 0402 Capacitator.
It is filtering some frequencies in feedback chain, and it is not affecting
normal
work for the device. So - all in all it can be OK to have it work without it -
just in some special occasions.

I soldered capacity, thanks to the support for the information.