Recently, I have seen the same problem on several 32-095 and 32-096 X-ray source controls which are used on older Physical Electronics PHI X-ray photo electron spectroscopy systems.

The issue is that C9, a 680 uF electrolytic capacitor blows out and the electrolytic material leaks out on the board.  Left unattended, the electrolytic etches and oxidizes the traces on the board.

If you have an older PHI XPS system that uses a 32-095 or 32-095 X-ray source control you should pull if out of the rack, remove the cover and inspect the board immediately.

If corrosion is present, then remove the board and remove C9.  Note the polarity of C9 as the + indicator on the board may be etched away.  Then, carefully clean the corrosion from the board as best as you can.   If in the shop I use some Alconox and let it sit on the board for a while, then rinse with DI water and let the board dry overnight.   In the field I have used isopropanol or methanol and cotton swabs.    Note that if the traces are corroded badly then they may come off the board as you clean it.  If so, you will need to use some fine copper wire to rebuild the traces.

Once the board is clean and dry, replace C9 with a new one.  I will dig into this issue some more and try to determine why this problem occurs so often and come up with a permanent solution.  In the meantime, I would recommend that the C9 capacitor be replaced every 5 years.

The pictures below show where C9 is located on the control board and what the corrosion looks like.