Bipolar capacitor replacement with very different dimension
10 mF means 10 milli farads or 10,000 μF (micro farads). Your replacement is possibly a thousand times too small in capacitance value.



I'd also have a concern about the letters "NP" after the 25 volt rating marking. There's a possibility that it stands for "non-polarized" so, you should ensure that any replacement is suitable.

Regards the use of "MFD"

I'd like to cite a few examples of a capacitor marked with "MFD" as representative of milli farads but I can't. Every example I've seen of a capacitor marked "MFD" has a value in μF (micro farads) so, I'm beginning to have doubts. Certainly the term mF is used in several places around the world to represent milli-farads.

So, erring on the cautious side, maybe the grey capacitor is 25 μF but it is so big because it might be non-polarized.