The caps have been fitted, Ansar Supersound (PP) for the midrange bandpass, a Mundorf Supreme (PP) for the series tweeter and Mundorf Ecap (Lytics) for the parallel pair in the low frequency filter. The Supremes are a bit pricey, but I only needed a 2.7uf so not too painful, its the big one, with the two Mundorf Lytics behind it. The three small Ansars on the right are 1.5 + 1 + 1 = 3.5 (3.48 actual). The Ansars on the lower left should make 21uf and are 8 + 6.8 + 6.8 = 21.6 (21.29 actual). The Lytics 47 + 47 = 94 measured 95.4uf. The 2.7uf Supreme measured 2.71, so all values are very close to ideal.
I replaced the bell wire between the binding posts and the x-over with Van Damme 2.5mm square OFC, I soldered it to the back of the posts. I left the internal wire as standard, as best as I could measure, the bass driver is wired with 15 AWG which should be up to the job.

Listening results for the Re Capped speakers.

I listened to many tracks on a Sugden CD21 and on my Turntable, via a Sugden A21a Integrated Amp and also through a Croft Micro 25 Pre/Phono and Proton AA-1150 Power Amp.

As a starting point let me try and describe how the NS1000M sounded before any changes:

I found there was a tendency to favour the upper frequencies, with the midrange and tweeter sounding forward and slightly edgy with the lower frequencies sounding slightly detached and lacking a bit of energy. I used the level controls to compensate and for both upper drivers adjusted to ten to the hour; 12 o’clock being flat. This is what a lot of people end up doing and probably fuels the comments that careful amp matching is important with these speakers to avoid brightness. I would rate my kit as fairly neutral in presentation, so will not comment further on that, only to say that my gear/speakers seemed to fit this trend.

After the re cap compared to the original sound
The results were not as dramatic as when I re capped my Celestion 66’s, I think this is because the 66’s use quite a few electrolytics which would have deteriorated to quite an extent, hence the big improvement. The NS1000M use film caps (metalized paper) apart from the large value Lytics used in parallel in the bass filter. These film caps have a long life so will not have deteriorated to any great degree, but are not quite as good as modern Polyprops. I think this is what accounts for the smaller impact the changes made.

I now have both the level controls set to flat (Normal).
There is no longer any harshness in the treble but there still a slight prevalence towards the upper frequencies.
The mid range is warmer/richer sounding than before.
Overall a more balanced sound with no area standing out or dominating too much.
Trumpet and Sax are notably sweeter with no sign of harshness.
Piano notes have better timber and seem more realistic.
Bass has a bit more of a punch and better grain/texture.

The improvements were not night and day but overall the presentation is slightly more even handed and I would say more musical, from what is basically a studio monitor, the later being a trait which monitors are not renowned for. I would speculate that they are also more amp friendly now, though they have lost none of that crisp top end, which the beryllium drivers are capable of delivering. The Mundorf Supremes are doing a good job there and over all I would say the level of detail has improved slightly, but like I mentioned, nothing dramatic.

So a slight improvement in most areas with nothing negative to report.
I am very happy with the way this went.