I suspect in those cases where this fix fails it's not a case of the capacitor value only being close enough but much more likely that any one of the other vintage electrical components in the module that has failed in addition to / instead of the capacitor.
Luckily you get a second chance of success with a Nova II / universal ignition module and I've yet to read about anyone failing with both fixes.
There is also a third option but it's by far most expensive option and that's a direct replacement module sold by Saegenspezi:
http://m.ebay.co.uk/itm/190590733267?_mwBanner=1 which I believe are based on a universal ignition module and coil on a purpose made plate.
I've actually recently had 4 fails in a row which has taken my 100% success rate for the fixes to around 50%. I always try the Foggysail fix first and if that doesn't work then I use a Nova module.
At first I had two successes with the Nova modules and thought that the coil parts rarely failed. The last four that I have tried were unsuccessful with both methods of repair. One was from a points ignition using a Nova module and it would only spark a little at first and then nothing. Another had a very weak spark and I didn't even bother putting the saw together to try it. The last two had decent spark and the saws would start and run for a while but after using them a while they would be hard to start. I found that if I cleaned up the spark plug or put a different one in then they would go a little longer until I had to start it again.
Today I tried the two successful Nova fixes I had and found that I was able to mill a small log into building materials between using the two saws but there was some hard starting. I'm beginning to think that if the Foggysail fix doesn't work then it's likely the coil will not last much longer although I could be wrong. The ones I thought were successful gave me no problems at first but after using them a bit they started showing signs of ignition failure.
I had three successful Foggysail fixes and they all worked flawlessly with no problems and I used them a lot.
Other options that I have discovered are the Sagenspezi ignitions. There is one for around $110 shipped and there is another for around $65 shipped. The $110 one is a direct fit with the Bosch electronic flywheel and worked great for me. The $65 one is for a points ignition but I discovered that it's possible to use a Bosch electronic flywheel on a points ignition. The poles are the same but the key way and timing mark are different. Basically, advance the timing a flywheel key width (same as with Nova module) and it should work, it did for me anyway. So I believe that of you find a good points ignition then you can use your Bosch flywheel (if you have the right crankshaft) and the $65 Sagenspezi should also work but I have not confirmed it yet. I haven't tested this thoroughly, just started it and made a couple small cuts with a points ignition and Bosch electronic flywheel advanced one key width.
If you already have a Nova module then you could get a new coil but they cost the same as the $65 ignition so it's better to get the ignition because it has a new spark plug wire and switch wire also. The coil on the Bosch electronic has a different part number than the points coil but I believe they are the same.
If anyone has suggestions for the failed Nova module fixes then I'd like to try but I think the coils are toast unless all my modules are junk.