to the OP: rust kills the bearing, but make sure, like really sure, that it’s rust. it could be just a stain from lube or something. the fact that all of mozart’s bearings from duncan are rusted may mean that it just stained in a way that looked like rust.
Non-stainless steel bearings (such as those that come in many Duncans, cheap YYJs and a number of Chinese throws) often rust/tarnish. The bearings start turning black and leave a reddish colour on the string around the bearing. Not sure if it affects play, but if it bothers you simply replace the bearing with a stainless steel one.
Here’s my pitch for the idea that ALL yo-yos should be equipped with stainless steel bearings as standard equipment when they arrive new in the package. It should be an industry minimum quality requirement. I for one am embarrassed to learn Duncan’s products do not have stainless steel installed the day they come off the line. After all these are not some everyday, pedestrian item like a vacuum cleaner or can opener we are purchasing here, it’s a YO-YO!
I agree, though can kinda understand why cheap yoyos cut corners and come with non-stainless bearings. However I was unpleasantly surprised to see the stock bearing that came with my Exit 8 start to turn black. Duncan couldn’t even be bothered including a decent bearing for one of their premium throws…
That’s exactly right. I am a huge Duncan promoter. I really feel they have stepped up to the plate in the last few years to once again become competitive in the premium yo-yo market. To learn their Exit 8 does not arrive with a stainless steel bearing is a huge disappointment to me.
(I will hasten to add this caveat, I own several Duncan throws and have never experienced any problems with any of their bearings.)
There you go right there, you make an excellent point IMO.
(To be fair I suppose it would perhaps be unreasonable to expect a Mosquito or Speed Beetle to have a stainless steel bearing. Most certainly however an Exit 8 or MoMentuM should arrive with stainless. Anything in their Screaming Eagle line should.)
I have a few Duncan bearings that are tarnished to heck. One of them is 7 years old and is one the best playing bearings I have. Never been cleaned either.
You can clean the externals with fine steel wool. My guess is that is really the only part that is tarnished. The internals are probably ok. If in doubt, soak them in WD-40 for a bit, maybe an hour, then clean and lube in the normal manner.