High pitched hum from right speaker only

Got an old Technics package system. Turntable, tuner, amplifier, equalizer, and double cassette deck. Issue involves the equalizer. When it's turned on, I get a high pitched hum from the right speaker. The left speaker continues to work perfectly. Fortunately, the EQ in question has a switch that allows for it to be "off" without bypassing the unit itself, so I can alleviate this without plugging the turntable directly into the amp. However, it would be nice to see if this is fixable so I can use the equalizer.
Panasonic is no help. They can't find any records on this unit. Apparently it's so old, even the manufacturer forgot about it.
Other than this issue, it's a beautiful system and I'd love to use it to it's fullest capability.

Package system model number:
SC-A210E
Equalizer model number:
SH-8027