After "replace diode 1ss99" your sentence makes absolutely no sense whatsoever. Replacing a diode is fairly easy with the right tools. I've never heard of that particular type, but it would be good to know if it is a surface mount component or an axial lead thru-hole component. The next thing that would be nice to know is where it is located. Is it on a PC board is is it hanging out in the ether -- so to speak?