I decided to take the plunge and buy some of those white gears for the DCC600 off of eBay too.
Oh dear… all three they make intermittent noises during playback, and now the winding/rewinding sounds really awful, like a broken sewing machine. Not exactly an upgrade to the red gears…
I tried using a bit of grease, but it does nothing: all three gears have the same intermittent “schlepping”. sound. I also tried them on different 2nd gen machines, all with the same results.
And after some time, the recorder just stops. Apparently the gear puts too much of a strain on the motor…
I did however notice that the bottom plate of the gear is a bit on the rough side, not smooth at all. Would it help to sand them?
I had such sound when part of old gear was stuck in the plastic gear of motor pulley. Check the gear of motor pulley it it is clean and no parts of old gear are stuck there.