Audio Systems: sound, pioneer head unit, unit model

Question
while listening to music, the volume slowly gets lower and lower and sometimes abruptly gets low, say from volume 13 to volume 2. If i turn off the stereo and turn it back on it returns to its original volume only to go back down again?

I have a pioneer head unit model 4500, with sony explode 6x9's.

any help would be appreciated

Answer
Jeremy,

  how old is the head unit .. it sounds like the button is sticking or there is a problem with the button on the internal side of things .. give pioneer a ring see if they have had any problems with that model and if they can give you some better insight into it .. it doesnt seem to me to be a wiring problem but a problem with the internal structure of the head unit or buttons .. hope this helps you out sorry i cant do more but if you need anything else let me know

thanks