Looking at a 1982 GL500I. Was getting ready to take for a test ride and there was a strange clicking noise while the bike was rolling out. We shut the bike down and rolled the back back and forth and still the strange noise. It sounds like a spring being plucked. We messed with the rear shock by adding air and checking the bottom bolts but still unable to locate the source of the noise. Again this noise was made with the bike on or off, forward and back. The guy took very good care of the bike and has changed shaft oil and said that he just rode the other day and there was no noise. Any idea? I plan on using the bike to commute 96 miles a day for work so need it to be reliable.