isopropyl alcohol 99, Chemtronics ES835B , and a remover for water base flux,
what ever was used, it is very hard to get off.
I can tell, that the untouched parts of the set have OLD rma flux on them still.
this i almost never used any more in production, but was used a lot back then.
we use water soluble and no-clean,( lead free) I had to get special order leaded rma solder to work on this.
when the resistors were replaced, some unknown type of solder was used, and the flux mix caused a white scale that has to be almost scraped off, not alcohol or Chemtronics would really soften it much, I gave it a good try and got some off but was afraid of damaging things.
17 pF on the crystal? that narrows things down a lot ( so may options looking them up
)
i assume Mouser #: 520-HCA357-17X is the same?