I think gentle heat is your best option, either a cool iron or hairdryer/heatgun on low with some gentle massaging and patience
Well, the seats

are in

the heaters seem to work too. I wired the headrest speakers up in parallel and they work too


.
Overall a good job hit them with a heat gun and improved them a bit. Got some ‘Poorboys’ leather and vinyl protection on them. Funny thing is you can still make out the word YOKOHAMA in mirror writing where a tyre was resting on the driver’s seat pad bolster. I’m guessing it will improve with time. But they look pretty good. I’m keeping the car for at least 10 years anyway, I’ll be 63 by then

.
Sent from my iPhone using Tapatalk