Check out post number 12 on this page from a couple of years ago....
http://www.videokarma.org/showthread.php?t=246106
The idea this guy talks about works great! I've done this to several clocks since he made that post. I did it very recently to a really cool little Truetone... just a week ago... and now I can't hear a thing!
To add to what that post says... I find using a small sauce pan and a shot glass on the stove works great. Here's how i've done it....
1. Sauce pan on stove
2. Drop your motor in the shot glass... try to keep the gear to where you can see if from the top.
3. Place two toothpicks in bottom of sauce pan
4. Fill shot glass enough to cover motor
5. Place shot glass on top of two toothpicks in pan
6. Using a glass, slowly pour water in pan... at least enough to submerge half of the shot glass.
7. Turn on fire... if you're using gas, turn on just enough to keep the flame going. If you're using electric, you'll want to be just a notch above the lowest setting.
8. Wait about 30-40 minutes, come back an see if you're getting bubbles coming out of the motor.
9. Once you get some bubbles, keep the fire going another 15-20 minutes (or until the bubbles stop).
10. Turn off fire and allow to cool slowly for at least 10 minutes.
11. Using a small ladel, remove some of the water... perhaps half... and then pour some cool tap water in there. Let sit for another hour.... longer if you like.
12. Remove motor from oil and wipe off completely.
13. Shake motor around a bit, and then put back in clock.
You should notice a significant difference. I did this to several clocks, and either it reduced the noise by at least half, or completely!
Below is a pic to show what I would have set up on the stove (minus water in the pan and motor in the oil).
The reason for the toothpicks is just to keep the glass from sitting directly on the metal pan. The fire is just below, so I dont want to chance cracking or breaking the glass of oil. It may not anyway, but it's just an idea I thought was good for safety sake.
Also is a pick of the Truetone I did recently.