I highly recommend using 303 on your dash. I did some testing(non scientific though it was).
I picked a crack on my old dash and liberally treated one side with 303 and let it sit(note: this is not normal usage), wiped it down later, then added more. Repeated several times. Afterwards I was able to easily crack the untreated side with minimal force. The treated side I was pushing so hard i was afraid it would deform the whole area before it cracked.
303 does not advertise to put the spring back in your vinyl, but it does!