Where do you live? Looks like oxid... high humidity, salt or some pets [:'(] You can clean it or not, it wont affect sound or anything else, it just doesnt look good. You can use a oily piece of cloth and clean it.

 47uf or 50uf... dont care about this. Old electrolyt capacitors have up to +100% -50% tolerance. Use the same or a higher voltage. 

Fix the connector with some epoxy glue. 

Die_Bogener:

Where do you live? Looks like oxid... high humidity, salt or some pets [:'(] You can clean it or not, it wont affect sound or anything else, it just doesnt look good. You can use a oily piece of cloth and clean it.

I live in warm city appartement, but I bought this from auction and I believe that the speakers were stored in some cold storage at the country. The smell was exactly like out summerhouse and the medal pedestal was rusted. I noted already then that few speaker crews were lightly rusted but never took out the speaker until now.

 What a relief. Thanks. I was so depressed and believed that it would be too bad, I hoped that it would as easy as you say. The speaker itself is very clean except the back and I'll try to clean it better when I replace the caps later on. I didn't check if the other speaker is as bad but I guess it will be quite the same

Die_Bogener:

 

 47uf or 50uf... dont care about this. Old electrolyt capacitors have up to +100% -50% tolerance. Use the same or a higher voltage. 

Fix the connector with some epoxy glue. 

Thanks. I didn't gave it too much tought. Better already. I'll order the new parts to see if there's any difference. Making good even better. :) Is the one marked "FOR CROSS OVER - BIPOLAR - 25v 12 uF" any speciality? Does it make any difference to normal bipolar cap with same values?

 I'll try to glue it next time, now I had no glue to be found, but I'll prepare better for the next time.

Thanks for your help.