Kempe, could it be sprag gear?
If it's not slipping, and it's not tension it's all that I can think of that's left. Mind you, the difference between the 430 and 590 in the drive area is pretty immense and my knowledge is limited to a subscription to the manuals area and only about 3 weeks of owning a Scotty.
On the bearings - I was passing a bearing place and they supplied me with new bearings straight away. Cost me about $13. They just needed the code from the side of the original bearings. Just as well, I had to take one off with a angle grinder. From the advice on this thread I was on my way back from my mechanic (who couldn't remove it either).
