My HR824's have worked well for about 4 years. Recently, both speakers
have had the woofer cut out entirely. I found that cranking the volume for
a moment or two seemed to "unstick" the woofer and get it going again. (As
the volume is cranked, the woofer emits bursts of sound, as if struggling
to come on, hence my description of "unsticking.")

Anyway, I was able to get a spare woofer off ebay for $30, so I replaced
the woofer that had the problem more frequently. As soon as I put the new
woofer in, it started "sticking" but a shot of high volume got it going
right away. (

Because the problem is so intermittent (and the speakers are out of
warranty) I haven't brought them to my local Mackie repair joint. But that
might be the next step, unless anyone has some insight into the problem?
It seems the woofer may not even be the root of the problem.

Incidentally, I noticed some differences between the old woofer and the
replacement. I'll probably check with Mackie, but here are the details in
case anyone knows about this.

Old woofer marked:
490-001-00 2
04 ‡ 811

New woofer marked:
490-001-00
04 ‡ 703

Which suggests the "new" woofer may in fact be older, due to the lower
part numbers? Also, the "old" woofer had an additional magnet
(doughnut-shaped) epoxied to the back of the speaker. The "new" woofer
lacks this magnet. There's a definite difference to the sound; the bass is
not as strong on the "new" speaker. (By changing the bass response setting
on the back, I was able to get the bass closer to the other speaker.)

Perhaps Mackie's parts department will be willing to sell the magnet--but
of course they're not open at the moment. Does anyone know the details on
the speaker differences? Was the additional magnet a "retrofit" or
something like that?

--
Jedd Haas - Artist
http://www.gallerytungsten.com
http://www.epsno.com