Sounds like it pretty much has to be the bearings. you have to locate them and check for wobble. Any side to side movement indacates a bad bearing. Probaly a standard size ,easy to find once you have it out.

Many of the older furnace fan blowers have little oiling ports on the shaft and you use a zoom spout type oiler for it which will sometimes compensate a little for bearings that are going out - also make sure the squirrel cage is clean (dust can build up on them throwing them out of balance and eventually kill the bearings)

Zoom spout - www.zoomspoutoiler.com/

Thank you Dan, Thalia and Choc – you all were timely and insightful.

I’ve continued to do some research – which also confirms your good advice.

I made real progress last night:

I climbed ladder back into attic last night; removed yoke that holds motor in position:
- cleaned blades
- re-positioned and aligned yoke holding motor; tightened attaching screws
- I was also, for 1st time in long time, able to properly secure squirrel cage door (in the past, I just kind of had to jam it in place.

IT RUNS VERY NOTICEABLY QUIETER (he shouted with gratitude)

Next – I will attach one or two bungee cords to help reduce vibration and maybe place some rubber material under bricks that furnace sets on.

************************************************

Dan – good idea about cleaning blades. I can barely get a brush in, but not enough room to check accurately for bearing problems. I don’t really pick up any wobbly-ness or squeek to suggest bad bearings. I think the “out-of-round” is mostly just this poor old fan, but it could also have to do with the motor bearing (it’s a direct drive – no belt drive). I don’t see any way to pull motor out to exam it.

Thalia – (as Choc mentioned) there are two little oil feeder tubes which I apply oil thru pretty much every year with my “zoom” type motor oiler.
Not ready to go toward building a housing; would have to be careful about something that might create a pocket that might fill with gas. I would also want it to be of fire proof material - so it would be a challenge. The tightening bolts was a big part of what made things better.

Choc… - www.zoomspoutoiler.com/ This is just like mine. These are great for getting oil to hard to reach ports. I use it on my swamp cooler every year too.

********************************************************

Kind of hard to describe my set-up.

I wasn’t going to take a pic, but I was deleting some old digital photos when I came across this from 12/03. I posted it to flickr today; also attached two little note windows with additional info:

www.flickr.com/photos/mys.../275026154/

*****************************
couple links:

www.questargas.com/AboutNat...prep.html

www.diynetwork.com/diy/he_h...7,00.html

Thanks for all your help.

It's the fan as has been observed. Some have replaceable bearings some don't.

You gotta open it up and look.