[R-390] Low gain up to 8mhz

[K2LNU]

Hello R390 fans,
A friend of mine is experiencing a problem with his R390A.   He is an AM
buff and is experiencing low gain on his R390A on all frequencies below
8mhz.  With the calibrator on he sees 20 to 30 db on the carrier meter on
frequencies up to 8 mhz.  It is especially dead on 75 meters.   Above 8 mhz
he sees between 75 and 85 db on the carrier meter.  He swapped out HR 202
and did not see any appreciable improvement.   Any thoughts and suggestions
as to a fix for this problem is greatly appreciated.
73's
Bill K2LNU