Ice Trackball issue

[sshaw10]

Have had an Ice Trackball for several years, not used much.  Went to play Missile Cmd and wasn't tracking well at all.  Opened it up, everything is clean but I replaced bearings anyway and checked coder discs, everything is in excellent shape.  It's in an enclosed, space so not dirty at all.  Haven't changed any wiring from when it worked correctly.  Tried unplugging and re-plugging USB but no help.  I can spin each encoder wheel with my finger and the windows pointer moves a tiny bit and is shakey, but it does move so it's not dead.  If one wheel wasn't working I would suspect the emitter was bad but both at the same time, can't imagine that's the issue unless they both didn't work at all and then I'd suspect power issue fried them.  Windows 7, nothing I can find driver wise.  Can't imagine both wheels acting up like this, any other suggestions?

Thanks much.

[RandyT]

From our records, it looks like this was purchased about 8.5 years ago. 

It's very likely that the IR LEDs in the opto-sensors have reached the end of their useful life, as they typically have a much lower lifespan than normal LEDs.  It's important to note that when the system is on and power is active, those LEDs are active as well, whether the trackball is being used or not.  It may appear that they fail abruptly, but that really isn't the case.  They work so long as the output is sufficient, but below that point, there isn't enough output to satisfy the requirements of the receiver, so instead of producing a coherent pulse-train, it's basically putting out information which can no longer be properly decoded, so you get what you are currently seeing.