I recently changed my oil and found little peices of metal in the filter. some of them are atracted to a magnet, I read on thumpertalk that this could mean bearing failure? I can hear kind of a tapping noise from time to time at idle, not sure if its related but sounds like it to me. Should I tear it apart and change some bearing or is it normal wear and tear? How difficult is it to change out bearings? I change the oil and clean the filter every 3-4 gallons of gas.