Is the tape I use causing horizontal banding?

I have been using Panasonic MQ tape in my GL1's and GL2 for weddings, both 63 minute and 83 minute. My thought was it was better to be safe than sorry--so I use the best quality available. However, I wonder if the tape is causing problems. If my camera operators leave a GL1 on pause in the record mode for an extended period of time, shortly thereafter there will be horizontal banding recorded on the tape--this happens frequently and is reproducible in testing. This has occurred even right after the GL1's were cleaned and aligned by Canon. A Canon rep explained that this is caused by an excess of chemicals from the tape washing over the heads. The banding does go away most of the time after 10 to 30 seconds of recording, but occassionally it will be so bad that there will be no recording at all, just blue screen for 30 or more seconds. The timecode will even restart at zero! Eventually, the tape in record mode will clean the heads and the recording on the tape will clear up and be OK.

I heard another person comment they won't use MQ tape because it caused problems. So, is it MQ tape causing the banding because the chemical is placed more densely on the tape, and so it washes over the heads causing my problem? Or is there an alignment issue with both of my GL1's that Canon has not caught or fixed? Should I switch to PQ tape?

I've also noticed that I get the message, "Heads Dirty, Use Cleaning Tape" on my GL2 when I pause for an extended period of time. Very seldom is there an actual flaw on the tape, and I just push record again. Same cause?

When was the last time you actually cleaned your heads prior to switching?

Actually, I have been using the MQ tape for about 3 years. All three cameras have been serviced by Canon since I started usng MQ instead of XJ. I have used the head cleaner tape several times since the cameras came back from Canon. In fact, I use it every fourth wedding for the GL1's which I thought may be too often?? I use a cleaning tape less often for the GL2 because it will display a message when a head cleaning tape should be used, although I tend to ignore it every other time and have had no problem with GL2 footage. Do you think using a head cleaning tape more often for the GL1's?