I had a look at your frame grabs and the tape transport mechanism of your XL1 needs to be cleaned and serviced by an authorized Canon repair facility. Whoever did your recent service didn't do a very good job. Last year I took a Sony camera in to a repair place to get the heads cleaned and it came back in worse shape (recording-wise) than when I gave it to them. Then I took it in to Sony Repair and all was well.
People who work in these cameras have to know what they're doing.