I pulled the old bearings with the old cheapo bearing puller I mentioned above. The new (or "new quality") bearings ($4 shipped from ebay) went onto the shaft easily with no tools required. Getting the bearings with the armature back into the motor housing seemed like it might be difficult, but I put the armature with the bearings mounted into a freezer bag and let it cool in the freezer for several hours. After I took it out of the freezer the whole assembly slipped into the motor housing with gentle finger pressure. It's back together and running now, quieter than before, but there is some random bearing noise that comes and goes. I guess I'll just live with that.
-DS

Replaced the bearings in my fan motor today.Purchased Type R3ZZ import bearings NTN equiv.2.23 each run nice and quiet .I was lucky as the leads were nice and long and I didn't have to do any disassembly
Jim

To pull my bearing I used a Craftsman battery terminal puller. The bearing came off so easily I'm surprised I couldn't pull it off with my fingers.
Keith

It was noisy this morning after 24 hours continuous operation - I'm going to have to pull it apart again. I may have damaged the bearings pressing them on with my fingers. A new set is on order. I think I have a snap ring tool of the style needed to service the motor in place.

Dave Wise

I was able to pull the rotor out the front, but the rear bearing stayed. I sanded down a few nicks on the rotor, but it didn't help the noise. I think the rear panel acts like a sounding board. In later production, Tek added rubber mounts. I will try rubber washers and nylon screws.

The procedure I proposed for removing the rotor from the front turned out not to work exactly as I wrote it. I have edited it so nobody will be led astray.

Dave Wise

I rubber-mounted the fan bracket, and cut the noise by 60%. I created washers from old rubber antistatic mat material. Strip off the vinyl top layer. The remainder is soft and about 1/8" thick. From this, cut 12 disks with a one-hole paper punch. Then punch #6 center holes with a leather punch. Drill a 1/8"-deep countersink in the bottom of each mounting boss using a bit almost as large as the boss, then file off the straight-sided perimeter of the resulting hole. Relieve each rib slightly to reduce the odds of touching the rear panel. Now string two washers each onto three 1" 6-32 nylon flat-head screws, insert in the bosses, and put on two more washers. Mount the motor to the bracket, and screw the bracket lightly onto the rear panel. Tighten enough to compress the washers by half.

I traced the high-low switch wiring. In my scope, the common contact wires are colored 9/6 and 9/3, and the fan orange (3) wire would go to the 9/3. Just choose whichever common terminal is 120V away from the fan's blue wire (near end of the cap). There's a smooth-edge hole for wiring nearby, and it would be a piece of cake to reroute the orange wire through it and to the switch. But when I pulled on the wire, it didn't break, so I left it alone.

I think I'm in good shape.

Dave Wise

I installed my new front bearing this evening. It took less that 5 minutes to change the bearing and about 2 hours to retrieve the captive nuts that fell off (again) when I tried to install the fan shroud. After I retrieved the nuts I used silicone to glue them in place. The new bearing was very viscous and the fan wouldn't turn so I added a drop of synthetic oil to the bearing and spun the shaft by hand for a few revolutions, after a few seconds the fan started up. Now it so quiet I can't tell if its running. On a related note what's the best material to use for a filter?
Thanks everyone for the help.
Keith

My 453 has an Eastern Air Devices fan motor. Armature is tight and the motor won't run so it will have to come apart. Anybody know how this one comes apart? Appears like it could be a sealed unit but there is a small cap on one end with a very small hole off to the side. I hope someone knows more than I do right now so I don't ruin it attempting to get it apart.

Thanks, Greg

Sorry, Greg, can't help you there. Mine's an IMC, easily disassembled by removing a snap ring at either end.

Dave Wise

Greg, Have you tried contacting Eastern air devices? They have a website http://www.easternairdevices.com/
Keith

My fan motor seems to be history, the shaft is free but the motor does not turn. I think I will try a muffin fan unless someone has an extra that they are willing to sell?? Should the air blow into the scope or should it blow out??
Thanks
Lynn

The "general rule" of thumb is:

-- if there's a filter (mounted outside facing you) the fan is bringing air into the case. The filter prevents sucking dust/debris into the interior electronics.
-- no filter usually means the fan is exhausting warm air out of the case.

Thanks for the reply. That makes sense. If mine would of had a filter I might of figured that out....
Thanks again,
Lynn

Are you sure you don't just have a broken wire? Those wires are thin and I worry each time I mess with the motor that I will break one of them.
-DS

Thanks for the reminder, it has been quite a while since I checked the fan. As I recall, it was working, and one day I realized the fan has stopped. I have been using a muffin fan on the top vent to draw out warm air. However, it is noisy, slides around and vibrates and I have to remember to plug it in. It would be nice to have it working properly again. The next time my bench is clean enough to work on it, I will check it !!
Thanks
Lynn

I found a replacement Eastern Air Devices fan motor on eBay for $10 and just installed, fan is working FB now. Would still like to try to fix the old one for a spare.

Greg

I decided to update the info in case someone else also has an EAD (Eastern Air Devices) fan motor in their Tek scope which needs bearing service. I discovered the end caps simply pry off by inserting a suitable tool in the small hole in each cap. Once the caps have been removed you will find small snap-rings with shims which are removed in the usual way. The part number for the bearings is R3FF which denotes a sealed permanently lubricated bearing. Several on-line auction sellers are offering them for as little as $4 each plus shipping. Also available is the type R3ZZ which is a the same size and shielded (not sealed) bearing which will not only allow but require periodic lubrication.

just for grins I thought I'd toss in this pic of the lube port for older 500 series fan motors. The lead dress tool has a 90* bend on the far end
which is resting in the oiling hole. There is another oiling hole on the "fan end" of the shaft as well. These older motors had a big thick Felt
washer at the location of the hole which acted as oil reservoirs. I think they were supposed to be filled every hundred hours of operation or once a year which
ever comes first.

For the 500 type motor I believe you would use Non-Detergent SAE 15 Turbine Oil. Hammond Organ oil is of this composition. You could also probably purchase the 3-IN-1 Electric Motor Oil in the blue container with a picture of a electric motor on it. The 3-IN-1 Electric Motor Oil is Non-Detergent SAE20 oil.

Didn't know 3 in 1 made a "motor" oil. Regular 3 in 1 isn't much of an oil beyond just being handy.