Dash Pad Cleaning

Anyone have some experience with this?  I have a '67 with the original black dash pad.  It's in great shape, but there appears to be light colored crud stuck in the grain of the vinyl.  I tried brushing it with all kinds of cleaners but when it dries the stuff reappears.   Before I take to it with acetone, naphtha, gasoline and nasty stuff, I though I'd ask if anyone has cleaned theirs up successfully.  I'd really like to avoid spraying it with dye or paint if I could.

Thanks much.

Found the answer.  Scrubbing Bubbles Bathroom Cleaner.  It's strong stuff but it's what The Seat Shop recommends for annual cleaning of leather seats.  It cleans them like nothing else.  You wouldn't believe the dirt, nicotine, old wax and who knows what that came off of these things!  Spray it on and scrub with a nail brush. Wipe it off and rinse with a wet sponge. Got that vinyl pad and glove box pad looking like new.  Now I just have to find a UV protector type preservative that won't make them shiny.

It it's too strong and makes it fall apart tomorrow I'll let you know.

Thanks for the information Trainmaster! This will make a good reference for anyone going through the same thing in the future.