Sunn Model 8 Speaker Cab Problem

[evanla]

Hi,

This is my first post on this forum so bear with me. I'm about to bring my Sunn Model 8 speaker cab in to the shop for repairs, but before I do I was wondering if there's anything I can do at home to try and fix it myself. The problem is that it has this horrendous, extremely loud buzzing for any frequencies that are even the slightest bit low. I took off the front grill and couldn't see anything obviously wrong with it on the cone or anything (no tears, etc. despite it being from the 70's). All I can say about it is that it sounds like a very "physical" problem; by that I mean it sounds like something's literally buzzing against the cone, but I can't/don't know how to take off the cone myself to look. That's just what it sounds like though, not sure if that's the issue. If the buzzing were less severe than it is I'd continue using it, but it's such a bad buzz that it makes performing and even rehearsing impossible.

The head I'm using is a Peavey Musician Mark III that was recently serviced and is in working order. Thanks in advance for any help!!

-Evan

EDIT: I've attached a picture if that helps.

[EdBass]

You can take the speaker out by removing the screws in the gill and then removing the bolts that hold the speaker in. Once you remove the grill, but before you back the speaker mounting bolts out, check the bolts and see if they are all tight to be sure one or more hasn't worked loose over the decades. An air leak can cause that buzz.
Also you want the speaker bolts "snug" rather than "cranked down", and evenly tight to avoid distorting the speaker frame.