One well known mechanic from the PNW believes it is caused by people hanging too many keys & crap off of their ignition.

He recommends keeping your other keys separate. I only have 4 keys total on my ring, so I don't bother. But I know on my '84 that it was a mommy wagon before me. I can only imagine the crap she had on her key ring. If it's any relation to how much crap was under the driver's seat when I first got it... OMG.

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'95 E320 Wagon
'85 300TD "Puff The Magic Wagon" - SOLD
'19 Mazda CX-9 Signature - Wife's sled
'21 Morgan 3-Wheeler P101 Edition - SOLD
'95 E300d - SOLD
'84 300TD "Brown Betty" - Miss this one
'81 240D "China Baby" - Farm grocery getter