here's a copy of a private post to Herb... edited for artistic sake.
don't be too quick to condemn an AFM... i've got several posts on these in the archives but i'll relate a little to you now. it is my experience that one *cannot* use an ohmmeter to check the afm, despite what Bentley says. there are surface mount capacitors in there that charge and discharge as the wiper arm moves and the resistance jumps all over the place. even on a brand spanking new one, which i did buy :( use an oscilliscope or a fast acting DVM and measure the key-on voltage on the wiped output. look for voltage dropouts or non linear response. each afm that i have tested with resistance alone, has tested 'bad'! also, it is very typical for the carbon track to be worn down so one sees the fiberglass board. one can squeeze down the wiper arm to have it ride on a new area, but even this doesn't seem totally essential. what DOES make a difference, it cleaning the carbon track with a clean pencil eraser and then running a heavy weight cotton bond cardstock, eg a 'rough surfaced' business card, under the wiper and burninshing the wiper contact. let me know if you need clarification on anything. -dan
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