On Thursday, June 8, 2017 at 1:31:39 PM UTC-4, Cursitor Doom wrote:

If I can source a generic electrolytic of the same spec or better for
30 quid, why should I not use that instead of the bespoke replacement??

Many years ago, my Tek 7603 failed to start. I pulled the power supply out and was driven nuts by a simple DC voltage regulator problem in the power supply. A bypass electrolytic capacitor would have been the obvious solution, except this scope used at least a half dozen extra large Mallory built capacitors in parallel, and there's no way they all died together. Adding a bit of external capacitance though brought the voltage right back and the scope to life. Turns out those big caps were dropping out one by one over the years and gave no indication of anything going wrong as they did, until the very last one opened when the supply went out.

Why did I mention all of this? Because I just removed those big Mallorys and stuck in some standard electrolytics of maybe half the total value and taking up about a tenth of the physical area of the originals, and the scope still runs daily with a perfectly clean and stable trace.

In other words, I doubt you'll see any difference by doing what you instinct tells you. That cap may be very low ESR, have special impedance specs or ripple current specs, but I'd be stunned if it makes any real world difference with off the shelf caps. If it were mine, I'd use Panasonic FR series caps.