When on phono input, my bass driver on one channel is moving in and out, i estimate at some very low frequency as i can see it but not hear it. This is only on the turntable input, without the stylus even on the record. Swapping the leads round still leaves the problem on the right channel only. Unplug the tt altogether and the phono input is fine, just the usual gentle hiss. To make matters worse, this sometimes does not happen. Even at its worst its usable, i just worry about the poor cone. Speakers and amp are old, owned 30 years. Recent cartridge change and amp recap. The gear itself, speakers epos es14, amp audiolab 8000c pre and rotel rb850 power. Turntable nad rega 2 clone with AT vm95ml cartridge. All of the above regularly making lovely music ...just this one problem