Intermittent Humming during otherwise normal operation

[bobj0694]

I have a 10 yo Rheem natural gas furnace that generally works well. Occasionally, when the blower comes on, I can here a slight humming noise (while it is blowing hot air). I can hear it better through one of the ducts versus standing next to the unit as the burner noise is too loud. Anyway, sometimes it will hum for just a few seconds and sometimes it hums for two or three minutes before you can hear a clunking type noise and then the humming goes away. I put a new blower motor in the other day and that has made no difference. Could someone point me in the right direction on this??
thanks much
bobj0694

[skippedover]

Sorry dude, we're not allowed to provide instruction for DIY work.

[Rob_in_WV]

Just a quick question, did you think to install a new capacitor with the new blower motor?

[marvin]

i have been chasing an intermittant hum for the last 2 years &
just last week while clocking the meter the regulator started humming &
the owner shouted out the window that it just started again.
had the gas co change reg. & customer said its too quiet now to
go to sleep. might want to check the regulator