Accumulated swarf causes ignition failure

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Interesting problem. F650GS 2003 single, 60,000 miles. Stops without warning, won't start but sounds like ignition timing is out (backfires, spits back through throttle etc). Checked spark, injection pulse, compression, valve timing, all good, flywheel pulse generator resistance in spec. Eventually found this View attachment 284972when I took the flywheel cover off The accumulated swarf View attachment 284971had even built a nice little bridge to the RH bolt head.
I am, at present, comforting myself with the idea that 60,000 mils of accumulated swarf on a strongly magnetic component is OK and that the engine is not currently grinding its insides to death!
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[db1]

Update: It seems that there isn't supposed to be any oil in the alternator housing, and the sump plug has a BIG cluster of swarf on it. A bit of searching suggest counterbalance shaft seal/bearings are likely to be buggered. Anybody got any previous on this?
Houston................errrrrrrrrrr