I have recently picked up a pair of Beovox s45-2's after al the positive comment on this site. I have heard them play before I boght them, they played at first but now I moved them (gently, of course) there seems to be something wrong. One of the bass woofers doesn't work 100% anymore, but I searched the forum and found about the stuck bass driver problem, but that seems not to be te problem. If I push the woofer it does move, so it's not stuck. Instead, when they are in use, the bass woofer works for some time, stops working, starts working again, stops again etc. etc.

Does anyone know what might be the problem?

(Apart from that, I also am not that positive about them in general at the moment, they seem a bit dull, would a filter replacement really make such a huge difference?)

If you are unlucky, the magnet is falling off the back. I would take the woofer out and have a look. Changing the capacitors will certainly make a difference if they are dull. They should be crystal clear. If you are lucky, you have a loose connection. 

A loose connection, I agree.
Typically where the flex lead meets the coil copper wire. That will be on the outside of the cone
where you can see a solder joint covered in black, just where the flex lead comes through the cone
from the backside. Carefully scrape off the black paint to expose the solder joint and redo it.
Add a drop of glue, silicone or similar afterwards to avoid rattling.

Martin

I removed the woofer, to look at the connection, realised you ment the other "outside of the cone", put it back in and for now it works again... Won't touch it anymore  for the moment, but if the woofers fails again, I know what to do, thanks!