This thread covers a missing step in the WM-DD center gear replacement tutorial, which is essential in order to have a quiet mechanism. Applies to all WM-DDs with center gear type mechanism: WM-DD, WM-DDII, WM-DDIII, WM-D3, WM-DD100, WM-DC2, WM-DD30, WM-DD33. There are 2 separate issues in regard to gear wobble: 1. Vertical wobble (up-down); 2. Horizontal wobble (like it's out of round); The vertical wobble is adressed by sanding the metal retainer in order to eliminate the burrs near the threads. Use 800 grit sandpaper on a flat surface and rub the retaining disc against the sandpaper until the burrs disappear completely. Then you can wash the disc with water to clean it and dry it with a paper towel. NOTE 1: Tighten the screws lightly, too much force will deform the plastic gear, creating more vertical wobble. NOTE 2: The metal disc itself has wobble relative to the center hub, so you won't obtain perfection. The horizontal wobble is caused by center disc having eccentricity relative to the center hub. This eccentricity varies with every individual unit, some being worse than others. Solution is to file the inner part of the plastic gear so you create play between the gear and the disc. This way you can mount it on the disc in a way opposite to the eccentricity. 1. After filing, install the gear and tighthen the screws very lightly so the gear can still be moved around. 2. Install the center gear spring on the mechanism and install the center gear assembly, but without the 2 retaining washers. 3. Push the assembly down a bit, so it's centered on the shaft, but doesn't engage with any other gears. 4. Rotate the gear by hand (touching just the middle part of the disc) and observe how the edge of the gear moves relative to the smaller white gear or any other fixed point. 5. You will notice some high spots, observe those, stop the gear there and push it in the opposite direction. 6. Repeat until the wobble is reduce to a minimum. 7. Gently lift the gear assembly and tighten the screws without moving the gear relative to the metal disc.
Once again - gold!! I for one have experienced the wobble, and have spent lots of time and energy with different solutions for reducing it. Now we have a clear, repeatable step in the replacement process. Thanks as always @Valentin !
I want to update this thread with another 3 aspects: 1. Wobble can increase the wow&flutter figure when it's above a certain threshold; 2. In some cases, the gear might also need sanding if there are imperfections. 3. As mentioned in the tutorial, the center gear metal disc should be cleaned thoroughly before installing the new gear (as indicated in the original tutorial), as even a little bit of dirt or a small piece of hair can create a significant wobble; However, all gears sold by Marian are good and if you have problems with noise, the chances are you're not installing it right rather than a defective gear. Excess vertical wobble can also cause problems with FF/REW skipping. The hortizontal wobble will create a periodic gear engagement noise.
