Smelly softening woofer and midranges

Roger, how old is the speaker and what part of the speaker is getting sticky (e.g., tweeter, woofer)? If it's a woofer, try pressing it in with your hand (fingers spread touching the cone around the dust cover of the speaker) when the power is off. Any rubbing noise?

Ozfly, Speaker is less than a year old. Tweeter seems fine. There are two 6 1/2" woofers and a 5 1/4" midrange. Using your test method, the woofers were both quiet upon light compression. The midrange, however, made a rubbing sound-almost like the sound of a manual bicycle tire air pump, both on the in and out cycle of the test. The speaker's been off all day while I was at work. Nothing sticky noted now. Watcha think? Roger

Additionally, speaker sounds rather flat and veiled-certainly not clean sounding. Could be related, or perhaps an unrelated placement issue.

Would you consider unscrewing one of the smelly drivers? If yes, do so, DON'T disconnect it and place it on a stool (or any support). Drive the spkrs and check if the driver is heating up.
It sounds like you're overheating the voice coil -- but why is beyond me (dc entering the system? Coils shot??). As you say, you don't drive the spkrs too hard anyway...