If my memory serves there was a .1uf 630V cap on the old board that it was worth upgrading. I replaced it with a .2uf 600V teflon. There is a polypropylene cap on the new board same value, can I, should I, reuse the teflon on the new board? Thanks!
The value is chosen, along with the associated resistor (Cc and Rc), to stabilize the internal feedback network. They are not precision parts, but I don't recommend using different values. You can try it, it might work out well ...