First off, the book is very important. Everything you need to know is in there, somewhere. Surprising that it was misplaced.

We have a 2000 year 850. Some things have changed with different series's, so ours may be different than a 900. On ours, when the metal detector started tripping continually, there was a bearing getting loose on the front lower feedroll. This is where the magnet is, inside there.

Our first Claas, an 840, had trouble with the metal detector when it was brand new. That turned out to be that the bolts holding the wear strips on had become magnetized, probably from being tightened with an impact wrench. The dealer demagnetized the bolts by heating them in an oven, then we reinstalled them and tightened with a hand wrench only, no more problems.

The sharpening and shear bar setting has already been covered. The sharpener will not work if the stone is wore, determined by how many passes since the last time it was replaced and the counter reset. I usually leave the feedrolls running while I sharpen, that reduces the possibility of tripping the metal detector with grinding dust. Dealer said that more than once, someone has sharpened knives right away in the AM and then the metal would not reset-feedrolls with dew moisture on held enough filings to set off the metal alert.