I was running Avia's calibration disc this morning (hey I'm snowed in, and it's tedious and fun in about equal parts). At one point, the test disk runs low frequency sweeps through each channel, one at a time. It starts at 200 Hz and works down to around 20 Hz. The VP-150 and the M60 I use for the right front did great within their spec ranges. The M60 I use on the left front also performed well except for one thing - I got a metal-on-metal rattling sound at many of the freqencies throughout the sweep, even at some of the relatively high freqencies (i.e 150 Hz). I hope that it just means there's a screw somewhere that needs tightening... but I've not really ever been a take-it-apart guy, so I don't even know where to begin or what to do.
Any thoughts?
