Pressing softly with a towel or napkin yields excellent results, especially if you can be PATIENT. I purchased my 1987 XJ6 20 years ago. From the day I purchased it, the PO acknowledged the series of black lines along the ‘door facing’ side of the squab on the drivers’ seat. I purchased a package from Leatherique of rejuvenator, prestine clean, and biscuit dye. Then I asked a local Jaguar dealer whose services they used for interior work. They came to my garage and prepped and sprayed the seats, but claimed the black lines on the seat squab would return, which they did. Then I noticed the door panels and center console were darker and browner than the seats. I called Leatherique and asked them for advice. They suggested using a clean white towel and the rubbing technique. It worked very well. Ever since then I’ve been annoyed by the constant recurring lines appearing on that seat squab. Several months ago I tried an experiment. I sanded the area on the squab where the lines kept recurring. Then, using a clean white towel, I applied some ‘leftover’ Leatherique which I still had in my tool locker for more than ten years, to which I added water and shook vigorously. Over the next seven days,during which I did not drive the car, I dabbed thin coats of dye on to the seat squab panel, allowing it to dry overnight, then returning the next day to apply another coat. It’s been four months now since I did this, and I’m pleased to report the car’s interior, and that seat in particular, look practically new.