This has been a recurring irritant: one of the front door speakers starts cutting out partially at low to moderate volumes (the effect is sort of like shifting the balance almost all the way to one side). If I crank the volume way up, the speaker cuts back in and works normally for a time.

The car has been back to the dealer twice for this problem, first for the left side, then for the right side a few months later. The paperwork from both visits says that they replaced the speaker(!). Each time, the problem cleared up. Problem is, now the left side is cutting out *again*!

So...what's causing this? I had the head unit replaced for an unrelated problem with the cassette autoreverse, so we can pretty much rule that out. And I find it hard to believe that a speaker could wear out in less than a year -- we don't even use the radio that much! Is the connection somehow coming loose inside the door? Or is there a partial short? Or is it something else entirely?

Any ideas?