CELESTION SL6 Si - woofer replacement/repair

The woofer on one of my SL6 Si speakers has started "buzzing" on passages where there is heavy bass. Otherwise, I think it sounds fine. I assume the surround needs to be repaired, but that's just a guess. Is this something that can be repaired for not a lot of $? If so, any recommendations? Alternatively, could I just swap in a replacement woofer (if one can be located)? If that would work, any recommendations re: where to find replacement parts? Thanks!
If you really love the speakers, you will probably need to buy another used pair, and cannibalize them for the woofers. As you probably already know, Celestion can't provide replacements, and the rubber surround was a special and integral part of the driver design. I have owned 5 versions of Celestion speakers using this woofer over the years (I still own 3 pair), and for some unknown reason, the rubber surround, while feeling soft, and otherwise looking good, can develop small fissures that almost look like they were cut with a razor knife. The speaker will still play, and doesn't sound any worse as far I as I could tell, but if it got worse over time, it would have to affect performance. I don't know if this is the problem that you are having. Anyway, it hapened to one pair that I had, and that was after I sold them to a friend. He uses them as is. It happened to another driver in one of my other pairs, but at that time, I was still able to buy a replacement.
Best thing that you can do is try to find a pair that doesn't have surround problems, and swap the driver out. They are great little speakers aren't they?
Yes - they really are great speakers, though not my primary ones at this point. I think you're right about having to keep my eye out for an old set for sale to cannibalize. I suppose it's not too far-fetched to imagine someone ending up with just one speaker for some reason and looking to unload that. But I probably shouldn't hold my breath.
I didn't really think you would find one speaker, I was talking about buying a pair. They come up cheap enough to make it worthwhile if you really like them.
They aren't my primary speakers either, but they just have really great balance of performance virtues that makes music sound good, and makes you forget what they can't do.
You might be able to find someone to re-cone speakers with butyl surrounds. (Re-coning doesn't necessarily have to mean replacing the cone assembly-it can involve voice-coils and surrounds also).
I'm no chemist but I've noticed some white residue that seems to build up with these butyl rubber surrounds. I've been wiping it off with a damp cloth, and following that with an Armor-all treatment. And crossing my fingers. BUT, I believe that Armor-all has silicone, so keep it away from the woodwork,it can make refinishing very difficult (fisheyes lacquer) also could make touch-ups tricky too.
Have you tried to tighten the screws or bolts holding the woofers in place. Almost all woofers get loose eventually and need to be tightened up. The noise you're hearing is typical of the loose woofers.
Do NOT try to tighten them down hard.
Just tighten them down snug.
And if it IS the woofer, then recone the woofer, not get a new speaker. Reconing shops all over the place can do the speaker and replace the surround and or recone the speaker. Get both done at one time if reconing.
Give Bill Legall from Millersound a call to get his opinion on this situation;he is well known in the business and highly respected for his work.

1422 Taylor Road
Lansdale, PA 19446-1531
(215) 412-7700
If you have owned the SL series of Celestion speakers, you will know that these can't be reconed or have the surrounds replaced. The driver was proprietary to Celestion. It was unique in not having a dust cap (which was unusual at that time), and changing it for a different driver would no doubt change the sound of the speaker completely.
Elizabeth's comment is a good one. These drivers need to be checked for tightness on a regular basis. Also check the ribbed aluminum diffraction plates around the drivers for tightness.
You didn't say if you had found any cracks in the surround. If you have, and that turns out to be what is causing the buzzing that you hear, I think that the only alternative will be finding a used driver.
thanks for all the great feedback. what should i do (if anything) to determine what the source of the buzzing is? - i don't want to do anything to make things worse if i can help it, obviously. this may not be a good thing to do, but i very very gently applied a feather-light amount of pressure to the surround while it was playing and the buzzing went away - not sure what that might indicate.
"not sure what that might indicate"

It means the woofer is beat. Like Rleff said, get a hold of Millersound and have them fix the woofer.. They may be the best speaker repair shop in the country.
Fascinating reading for a SL6 fan. One of mine also goes "grrr" and I want to have it looked at. But how does one open the unit??
It isn't hard. First, unscrew the ribbed aluminum plate. Underneath that, the driver is screwed to the baffle. Carefully unscrew it, and you can remove the driver. It is hard wired though, so if you want to take it away from the speaker, you will need to cut or unsolder the lead wires. It is really packed with foam on the inside.
Thanks Roxy

Unfortunately my speaker is the SL6 (not SL6 Si) No screws are to be found once the aluminum plates are removed. The tweeter can be withdrawn, but the driver appears to by fixed to the baffle from the inside of the unit.