Hi Steve,
I had an output shaft problem with my brand new 04 550, it had 0.33mm end play.
The final fix was to replace one of the 1mm stop discs on the shaft with a custom 1.25mm disc that Dale Lineaweaver made for me, leaving 0.08mm end play.
The bike had never been ridden except for some minor amount by Motoxotica in their parking lot to rejet the carburetor before I picked it up. I started it once to make sure it ran and was surprised at the amount of noise it made. I had previously planned to remove the balancer on any new Berg that I might buy that had the existing balancer design. I noticed while removing the engine from the bike that the drive sprocket wobbled and was very loose (axially) on the shaft. I measured this to be 0.33mm. While reassembling the engine I noted that the 1st gear idler was rubbing on the side of the 5th speed idler and that by pushing the output shaft to the left side of the engine the noise went away. So I decided something had to be done to correct the excessive end play. I also doubted that the 0-ring on the shaft would seal with that much end play, so I changed the stop disc from 1mm to 1.25mm.
The 4th picture is in the next post.
Regards,
Joe