Voice of Music speaker problem

Hi--I have a V-M 560A with an aux speaker. The aux speaker sounds fine, but the speakers in the main cabinet sound slightly distorted or 'fuzzy' at times. This is less noticeable at a higher volume, and doesn't seem as obvious after a long period of use.

Does anybody have any ideas what may be causing this?

The only thing I can think of right now is your Aux speaker is much better, maybe not as old as original speakers? If you are getting good sound thru the aux the tubes/parts are ok it seems. Dust gets everwhere. You might try cleaning the speakers...I don't think these speakers had dust covers.

This is probably a blown speaker, although it might be full of dirt. Also check to see if anything is touching the back of the speaker (such as a cable).