@Dallas Joseph posted:You are taxing my eye to brain neurons and rods on a late Saturday Rod.
Well.... compaired to my ABA F units your B has smoke , mine does regular non smoking dummy running.
If my eyes are not too badly damaged I seem to notice what looks like a cover on the end of the diaphragms on the A units.
I hope some " keen observer "
chimes in to help out .
Dallas you nailed it; all 3 units are making smoke! Just added that recently. Good thing I took the winter cover off my train room exhaust fan yesterday. That should keep the peace upstairs! Haha. I don't think there is any cover on the diaphragms, but one or two might still have the white foam insert.