They are ok on lo power applications, I think they can take around 5or 6 Watts.
For that you get quite a bit of sound as they are fairly efficient.
The backs come off quite readily, you will need to wear some long sleeved gloves or you will be itching for a week from the rockwool filling.You will need to remove the rockwool filling, it's glued in but it may have come loose over all these years.If not, use a spatula to get under it and lift it. Yoiu will need to glue it back in place when you finish the whole job.
You can then get the front off, the screws holding it in place are on the inside, I used a vacuum once I had the rockwool out, just to get the remaining fibre dust out.
The replacement capacitor does make a significant differance to the sound, but ultimately you wil not get true hi-fi sound of of them but they are pleasant enough.
You can detach the speaker elements and very simple crossover in one, the capacitor will need replacing.
To clean the front cloth is not easy, because if you wet it too much then it will come unstuck from the backing board. I did this and has to stick the edges down with imapct glue, and I also had to staple it down tight so that it would not ruckle up when pushing it back into the main case.I suppose you could use that car interior cleaning foam, but I an not keen on the idea as it has lots of chemicals in it, its quite aggressive.
I used ordinary soap which lifted out the nicotine colouration and it left me with a nice new looking set of grilles.