I redid mine this year for my 208. It is kind of a big job and you need an industrial sewing machine. The materials ran about $250 including new foam. I used the same pleated material that the originals were. If you could get them done for a few hundred more, that would seem to be worth it. My bolsters were secured by two screws only, one in the rear and one towards the front. Feel behind the gunnel for the screw. It is actually inserted through the grommet so once you find out which grommet was used, you put a philips screw driver in the hole and play around until you find the scew head. Then unscrew.
After you remove the two 0r three screws, the bolster slides up. It is suspended on several metal 'hooks' that slide into holds on the plastic backing of the bolsters.
One work of caution if you decide to remove the old vinyl: My bolsters although they looked dry ( cracked and stiff but dry) were filled with mold inside. It was nasty mold at that and you should take precautions.
The original foam was wrapped in clear plastic to keep water out but over time, the plastic gets degraded or ripped. The foam gets wet and moldy. For the new job, I used a foam called Dry Core which doesn't hold water. The stuff is expensive but you don't have to wrap it to make it water 'proof'
