All. I have just repaired a new ETX for a local school. Whilst still with the tissue over the OTA the plastic ring that holds the gearbox to the shaft on the RA worm has snapped. I glued it back together and glued some string around it to spread the load. I have some spares from a previous repair and the older ETX had blue plastic for the gearbox casing and this new one black. Not interesting, but the blue plastic looks a bit thicker around this part and less prone to snap. Now, the older part is better made and survives longer. As this is an internal part, human activity is not a factor on its life. I had the same on two motor bikes, 10 years apart and the same model, the older dust caps lasted longer than the new ones, in front of me I had 14 year old dust caps good as new and 4 year old ones splitting. It is as if failure is being put into newer versions. Kind regards, Mike.
It's a common failure. I don't think there's any difference in the gear boxes other than the color. If I was desperate for the part it look like something could be done with some aluminum and a ball bearing. I just set my last spare off to Cyprus! Here's a Alt motor getting a real bearing before being asked to do some heavy liffting.