[Jamesp]

Because the IMS is a sealed assembly here should not be any communication between the engine oil and the inside of the IMS. That means the inside of the shaft should be dry, the fact that they are frequently full of oil is just a symptom that there is another problem. Oil can be forced through the bearing seals washing out the grease of the OEM bearing which greatly limits life. I suppose if the press fits are failing oil could enter there as well. The fact that the chips are on the inside of the shaft behind the bearing seal makes one think they may have been generated inside the pressed on shaft. There have been threads with borescope type cameras on this thread recently. You need one of those. Clean out the inside of the IMS tube and look at the interface between the pressed pieces and the tube assembly. A magnet is not effective in pulling chips off a ferrous surface. I'd go in with solvent and a cloth (not paper towel) followed up with a dry microfiber cloth to trap the fines. As the particles are in the tube, it is likely you will see damage where the parts meet inside the tube if you use a borescope camera. That beats splitting your engine case by a mile. Sorry to see you're having this trouble.