Have a JB that went microphonic at some point after fiddling with various magnets and pole pieces. I potted it with some white odourless candle paraffin and the problem went away. Still sounds great, but I'm keen to learn more on this subject nevertheless.it doesn't perfectly penetrate the windings , anyway it works in most of the cases and it's however better than an unpotted pickup if it gives you problem (I always think unpotted pickups sound better, but I recognize there are environments where they are a PITA to work with) .