| Years ago I took your route and completely dismantled my unit as well. If the motor runs well in one direction, but not in the other, logically the timer sounds like the culprit, but you've already replaced that. Sounds to me like the armature (the spinning central part of the motor) needs attention, or the brushes, or both. Where the brushes rub on the sides of the armature causes wear and dirt collection over time. The fix is to clean it up. To do that you need to remove the end plate holding the brushes from the motor. Then you can service the brushes as well as the armature. You may be able to remove the armature from the motor case. If not, service it inside the case. Use fine sand paper and sand around the circumference of the armature where the brushes contact it to smooth the ridges out. Then use a dental pick or similar to clean out the spaces between each section of the same area of the armature. Be careful not to nick any of the fine wires between each section. Lastly, wrap the same sandpaper around a tube /pencil/rod about the same diameter as the armature and lightly sand each brush. Then assemble the motor and test it. Hopefully it should now operate correctly in both directions. Hint: The brushes are spring loaded. Push one into its cage and hold it with your finger while you do the same for the other brush. Then place part of a toothpick between the two brushes to keep them in place BUT SLIGHTLY FARTHER APART THAN THEY WOULD BE WHEN RESTING ON THE ARMATURE when the motor was altogether. This makes it easier to slide the end plate with the brushes onto the armature. Then just before you seat the end plate home, use needle nosed pliers to pull out the toothpick. I've used this same procedure on power door lock motors, power wind motors and power seat motors as well over the years. It takes a little time and patience, but saves a whole lot of cash. Good Luck!
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