Fingers crossed!
My father told me once to "let working dogs lie" i.e. don't meddle with them. I've made the same mistake a number of times so I agree
. Then he died and left me a whole pile of homebrew equipment that doesn't work any more. He built a DVM, power supply, function generator and a frequency counter. All of them were built by ripping off Heathkit designs with even more cost savings (i.e. buying hooky bi-pre-pak transistors and reject ICs). I am slowly going through rebuilding them and they still don't work! I've reverse engineered the frequency counter so far so I'm just going to admit defeat and build a copy of it. Seems to be loosely based on the PW September 1971 design but with LED displays.