Capacitors can sometimes measure the right capacitance, but become electrically “leaky” at higher voltages. If you don’t have a tester that tests for leakage at 400 volts, I’d try it and see if it works, but if you have weak or no spark, it still can be bad. I use a Heathkit Capacitor Checker from the 1960s that I assembled back then when I was a teenager. If anyone out there is interested – these come up on E-Bay occasionally. Here is what it looks like: https://www.californiahistoricalradio.com/restorations/heathkit-it-28-restoration/
Dave
