[Jukebox-list] Define hum?

[dguarino1]

I am wondering if someone might be able to define hum for me. I have a
Wurlitzer 2900 that "used to"  hum though the speakers. More volume, more
hum. I have since recapped the amplifier with one of Vern's kits and the hum
from the speakers is gone. The music sounds much, much better! I couldn't be
happier. But (here it comes) now I have a hum when no records are playing.
It gets louder the longer the jukebox sits power on, not playing. The hum is
not coming from the speakers nor the lighting transformers. It makes no
difference with the volume up or down. It gets loud enough for someone else
in the room to ask why its humming. I have cleaned all the contacts, new
cartridge and needle, replaced the power cord, new belts, new tt mounts and
several selector solenoids proir to this new hum. I have disconnected the
audio inputs and speakers and its still there.
Could this be harmful to the jukebox? The jukebox is currently not being
played as its in Texas and I am on the east coast. Just wondering.....

Thanks,

David G