91 200T radio problem

[Bob Hawkins]

My radio system which is the 4 speaker Bose set-up will not produce any
audible stations.  It will squawk and squeal then the volume declines to O.
I have no access to a tech that can check the speaker or head unit.  Should
I replace the head unit with a reman. or the speakers or just put in a whole
new system?  Any one with some experienced advice will be appreciated.
Thanks Bob