I have two Roland VS-880's that will not record. One records only channel 2, 3, 5. the other does not record at all. Both where working perfectly until I started messing with effects on one channel at a time. The one that records, play back is correct, add effects to working channels is correct. They both have the effects card. Any help? I cannot find a single person that will work on these units. I know that they are old but when working you cannot beat them for recording. I have been asking if there was a battery in these units, no response. I asked if the hard drives can be damaged in any way, no response