I had a look at my bolsters with a view to applying some Zymol Leather conditioner. yesterday I applied by hand and left it, looks ok.
But tonight i went one better, got the heat gun, and warmed the bolsters, then applied by hand again, and heated gently as i worked it in.
My inside bolster was not bad, but had slight rippling, they have virtually all gone, and the Zymol has really worked in well. The drivers side had very little rippling, and they all went totally.
i was very careful not to apply too much heat, and not let the heat gun linger on one point too much.